On 10 September 2005, she won the 10th HSBC British Wee Wonders Championship by 11 shots at the Balgove Course, St Andrews, Scotland, with a finishing round of 61. Two months later she finished runner-up to her sister Lisa in the Young Masters Golf Junior Series at La Manga in Spain. On 1 June 2007 at the age of 12, Maguire broke the record as the youngest golfer to participate in a
Ladies European Tour event. She played in the 2007 Northern Ireland Ladies Open at Hilton Templepatrick Hotel & Country Club. On 21 May 2008, she won the Lancome
Irish Women's Amateur Close Championship at Westport, County Mayo. In the same year she won the Irish Women's Amateur Golfer of The Year award, the youngest ever winner aged just 14. Maguire won the
Portuguese International Ladies Amateur Championship in January 2011 by 15 strokes. Later that same year, Maguire won the
Irish Women's Open Stroke Play Championship. In the same year she won the Irish Women's Amateur Golfer of The Year award for the second time.
2012 Maguire became the first Irish golfer to win the Irish Girls Open Strokeplay championship, held at Roganstown Golf Club in April. She beat an international field by eight shots. She was part of the Great Britain & Ireland
Curtis Cup team which defeated the US at
Nairn, Scotland by 10.5 points to 9.5 points in June, shortly afterwards winning the
Irish Women's Amateur Close Championship at the County Louth Golf Club, for the second time in her career.
2014 Maguire left secondary school at Loreto College,
Cavan, in Ireland with top scholastic honours and joined
Duke University in
Durham, North Carolina, U.S. At Duke one of her classmates was the American professional basketball player,
Grayson Allen.
2015 Maguire commenced the year in spectacular form in NCAA college golf, shooting up to first place in the World Amateur Golf Ranking on 13 May. In the Darius Rucker Intercollegiate held at
Hilton Head, South Carolina, on 8 March, she came first with rounds of 73, 65, and 69. In the
Atlantic Coast Conference (ACC) Championship held at
Greensboro, North Carolina on 19 April, she won with rounds of 68, 68, and 70. In the NCAA South Regional held at the Warren Golf course,
South Bend, Indiana on 9 May, she won again with rounds of 72, 68, and 72, helping Duke win the NCAA South Bend Regional title. On 6 May, she was voted the ACC Player of the Year and ACC Freshman of the Year. Maguire was a selection for the 2015 ACC All-Star team. She also won ACC Golfer of the Month awards for both March and April. On 25 May, she won the 2015 Annika Award for the best golfer of the year in American college women's golf. On 20 May, she was chosen as a member of the South Bend Region All-Star team. On 26 May, Maguire was honoured both as the Women's Golf Coaches' Association (WGCA) Player of the Year and Freshman of the Year for 2015 and was included in the 2015 WGCA All-American team. She was also the recipient of the 2014–15 Golfstat Cup presented to the player who has the best scoring average. Maguire's stroke average of 70.78 was the best in the history of Duke University women's golf. She tied the Duke record of 24 par rounds or better in a season and the university's record for most wins in a season with three. At the British Ladies Amateur held at
Portstewart,
County Londonderry,
Northern Ireland on 11–13 June, Maguire won the stroke play part of the competition, finishing 6 strokes ahead of the field with rounds of 67 and 68. She also helped Ireland to win the international team event. On 25 June, Maguire was named on the 2015 All-ACC Academic Team which recognises academic as well as athletic excellence. The same month, she won the Golfweek National Player of the Year award and was selected to Golfweek's All-America First Team. On 6 July Maguire was named on the WGCA 2015 All-American Scholar Team. On 27 July, Maguire represented Great Britain & Ireland in the
Vagliano Trophy against Europe, held at
Malone Golf Club,
Belfast, Northern Ireland. Europe won with 12.5 points to 11.5. Maguire was undefeated, contributing 3.5 points of the GB & Ireland total. Maguire was invited as a guest amateur to play in the European Ladies Tour's
ISPS Handa Ladies European Masters held at Buckinghamshire Golf Club,
Denham, England on 2–5 July. She stunned the professionals by finishing second, just one shot off the lead with rounds of 69, 70, 69, and 69. As an amateur Maguire could not accept the prize money of €50,000. In her last seven stroke-play competitions, she finished 1st, 3rd, 1st, 1st, 2nd, 1st, and 2nd. On 20 August 2015, Maguire was awarded the
Mark H. McCormack Medal given annually to the number-one-ranked female amateur player in the world. Maguire was invited to play in the fifth and final major of the year,
The Evian Championship held at Evians Golf Club, Evian Les Bains, France, on 10–13 September. Maguire finished as leading amateur and became the first woman ever from the Republic of Ireland to make the cut in a major. Again as an amateur Maguire could not accept her prize money of €18,648, meaning forfeited over €68,000 in prize money in 2015. Nonetheless, she was included in the top 300 of the
Women's World Golf Rankings. In September Maguire was awarded the European Ladies' Amateur Golf Ranking's gold medal. In December she won the Irish Women's Amateur Golfer of The Year award for the third time.
2016 On 12 June 2016 at
Dún Laoghaire Golf Club, Maguire was part of the Great Britain & Ireland team which defeated the US in an 11½ to 8½ win in the 2016
Curtis Cup. She contributed 4 points to the winning total. On 21 June, Maguire was selected on the All-ACC Academic Team for the second year in a row. In June, Maguire was selected to Golfweek First Team All-America for the second straight season. On 5 July Maguire was selected for the 2015-16 WGCA All-American Scholars Team which recognises academic excellence as well as athletic excellence, for the second year in a row. On 31 July at the
Woburn Golf and Country Club in England, Maguire won the Smyth Salver when she finished as the leading amateur at the
Ricoh Women's British Open, one of the
major championships. As an amateur, she forfeited her 25th place prize money of $25,500, after rounds of 71, 70, 68, 75. In the last 12 months, she forfeited over $100,000 in prize money as a result of her amateur status, despite playing only a handful of professional tournaments. As a result of the points earned at the British Open, she regained her world number one amateur ranking on 3 August 2016. On 15 August 2016, Maguire was awarded the
Mark H. McCormack Medal given annually to the number one ranked female amateur player in the world. This is the second successive season Maguire has won the award. On 20 August Maguire finished 21st overall and was the leading amateur at the
Rio Olympics Women's Golf for a two under par total of 282, with scores of 74, 65, 74, 69. On 17 September, Maguire helped Ireland to a third place bronze medal in the
2016 Espirito Santo Trophy held at Mayakoka El Camaleon Golf Club in Mexico. Maguire finished in a tie for 6th place in the individual rankings with rounds of 72, 70, 71, 69 for a 6-under-par total of 282. On 28 September, Maguire was awarded the European Ladies' Amateur Golf Ranking's gold medal for the second successive year. On 2 November, she helped Duke win the East Lake Cup held at
East Lake Golf Club in Atlanta, Georgia, USA, beating Washington State in the final. On 28 November, Maguire was chosen as a member of the Global Golf Post All-Star amateur team of 2016. On 3 August, Maguire announced she would turn professional after the
Brazil Olympics and would enter the LPGA Tour
qualifying school in October. After successfully completing stage II at qualifying school, Maguire withdrew prior to stage III and stated she would return to Duke. In December she won the Irish Women's Amateur Golfer of The Year award for the fourth time.
2017 She won the ACC Championship for the second time on 15 April with rounds of 68, 72, 70. It was held at the Reserve Golf Club, Pawleys Island, South Carolina. Maguire was selected as ACC Golfer of the Month for April 2017, which is the sixth time she has won the monthly award in her college golf career. On 11 May, Maguire was voted the ACC Women's Golfer of the Year for the second time in her career and was also selected for the All-ACC Women's Golf Team for the third year in a row. Also on 11 May Maguire was selected for the College Sports Information Directors of America Academic All-District III Women's At-Large Team, which recognises the nation's top student-athletes for their combined performances athletically and in the classroom. On 23 May, Maguire was named the USA Women's Golf Coaches Association (WGCA) National Player of the Year for the second time in three years and became just the fifth player in history to win the award multiple times. She was also selected for the WGCA First Team All-Americans. On 24 May, Maguire was awarded the 2016-17 GolfStat Cup which is presented to the player with the best scoring average versus par with at least 20 full rounds played during a season. It was the second time in her career to win the cup. Maguire also finished in first place on the Golfweek/Sagarin women's college end of season rankings. On 8 June Maguire won the Annika Award for the second time, becoming the only person to win it twice. She was also selected on the CoSIDA Academic All-America® Division I Women's At-Large Team, only the second Duke golfer in history to be so. On 17 June, Maguire won the
British Ladies Amateur Golf Championship for the first time, beating Ainhoa Olarra of Spain 3 & 2 in the matchplay final held at the Pyle & Kenfig Golf Club,
Waun-y-Mer,
Wales. On 25 June, Maguire was named the ACC Women's Golf Scholar-Athlete of the Year and was also named to the All-ACC Academic Team for the third year in a row. On 28 June, Maguire won the Golfweek National Player of the Year award for the second time in her career and was also selected to Golfweek First Team All-America for the third straight season. On 6 July, Maguire represented Great Britain & Ireland in the
Vagliano Trophy against Europe, held at
Circolo Golf Bogogno, Italy. Europe won 15 points to 9. Maguire contributed 1 point of the GB & Ireland total. On 5 July, Maguire was selected for the Women's Golf Coaches Association (WGCA) All-American Scholars Team for the third year in a row. On 10 July Maguire was awarded the 2017
Edith Cummings Munson Golf Award by the Women's Golf Coaches Association (WGCA). She is only the second golfer in history to win both the Edith Cummings Munson Golf Award and the WGCA Player of the Year in the same season. On 6 August, at the
Kingsbarns Golf Links,
Scotland, Maguire made the cut and was runner-up for the Smyth Salver awarded to the leading amateur at the Ricoh Women's British Open, one of the major professional championships, after rounds of 69, 71, 70, 75. On 15 August 2017, Maguire was awarded the
Mark H. McCormack Medal given annually to the number one ranked female amateur golf player in the world. This is the third successive season Maguire has won the award thus equalling the all-time record holder
Lydia Ko. On 12 September, Maguire began the 2017-2018 College Golf season by winning the Jim West Challenge at The Fazio Course at The Club at Carlton Woods, The Woodlands, Texas, USA. Her rounds of 67, 63, 70 for a total of 200 included the lowest round of her career, a 63, which is the second lowest round in the history of Duke University, one stroke behind
Liz Janangelo's 62. Maguire's 36-hole and 54-hole totals of 130 & 200 also broke the Duke all-time scoring records for two and three rounds. Her 13-under par total of 200 also broke the tournament all-time record. She also helped Duke win the team title at the tournament as well as setting a new school team scoring record of 33-under par total of 819. Duke also set a new Jim West Challenge tournament record for under par (-33) and 54-hole score (819). This is Maguire's fifth title of the calendar year 2017.player – Jim West Challenge On 22 October, Maguire qualified to play in the professional
Symetra Tour in 2018 by finishing in ninth place at the
LPGA Qualifying Tournament (Stage II) with rounds of 70, 69, 70, 72. She finished as the second highest amateur. On 9 November Maguire was selected as ACC Golfer of the Month for November 2017, which is the eight time she has won the monthly award in her college golf career. On 27 November Maguire was named 2017 Global Golf Post Female Amateur of the Year. She was also chosen as a member of the Global Golf Post All-Star amateur team of 2017, the third year in a row that she has been selected. In December she won the Irish Women's Amateur Golfer of The Year award for the fifth time, equalling the all-time record held by Claire Hourihane.
2018 On 31 January, Maguire broke
Lydia Ko's record for the most weeks at the top of the World Amateur rankings, with 131 weeks. On 28 February, Maguire was named as an honorary recipient of the ACC Weaver-James-Corrigan postgraduate scholarship, which is awarded to selected student-athletes who intend to pursue a graduate degree following completion of their undergraduate requirements. On 14 April at the Liz Murphey Collegiate Classic in Athens, Georgia, Maguire broke the all-time ACC record of most even or under par rounds in a college career. Her record of 80 even or under par rounds (she eventually finished her college career with 87 such rounds, the second best in NCAA history) also breaks the Duke record held by
Amanda Blumenherst. On 23 April, Maguire claimed her third win of the 2017–18 college season by winning the ACC Championship for the third time in her career, which matches the all-time record of Amanda Blumenherst. She finished with a total of 210 and won on the third hole of a playoff against Duke teammate Jaravee Boonchant. She also helped Duke to win the ACC team title for the second year in a row. Maguire also matched the Duke 18-hole record for the ACC Championship with a five-under 67. It tied Brittany Lang (2004 on par 71) and Maria Garcia-Estrada (2000 on par 72). Her round of 67 also broke the ACC Championship course record at Grandover Resort. On 23 April Maguire was presented with the
Duke University Lifetime Achievement Award. On 3 May, Maguire broke the all-time record for most ACC Golfer of the Month awards when she was selected for the ninth time. On 4 May Maguire was voted the Atlantic Coast Conference Women's Golfer of the Year for the third time in her career. She was also chosen for the All-ACC Team for the fourth time in her career. On 8 May Maguire broke the all-time
Duke University record of most rounds in the 60s. Her score of 65 at the 2018 NCAA Women's Regional Championship, held at the University Ridge Golf Course, Madison, Wisconsin, USA, was the 31st of her career in college golf, beating
Amanda Blumenherst's record of 30. On 10 May, Maguire was inducted into
Phi Beta Kappa, America's oldest academic honor society. On 11 May, Maguire was awarded the ACC Plaque for Excellence, Scholarship and Athletics. Maguire's final 70.97 college career scoring average is the best in NCAA history for any female golfer with at least 100 rounds. On 22 May, Maguire was selected for the USA Women's Golf Coaches Association (WGCA) All-Americans First Team. On 23 May Maguire was selected CoSIDA Academic All-District III for the second straight year. She was recognised for obtaining a 3.943 grade-point average along with a degree in psychology and a certificate in markets and management studies. On 9 June, Maguire was selected to Golfweek First Team All-America for the fourth season in a row. On 13 June, Maguire selected on the CoSIDA Academic All-America® Women's At-Large Team for the second year in a row with a Grade Point Average of 3.94 or A. On 20 June, Maguire was named the ACC Women's Golf Scholar-Athlete of the Year for the second year in a row and was also named to the All-ACC Academic Team for the fourth year in a row. On 4 July, Maguire was selected for the 2017-18 WGCA All-American Scholars Team which recognises academic excellence as well as athletic excellence, for the fourth year in a row, a Duke University record. On 6 July, Maguire was selected on the annual ACC Honor Roll for the fourth year in a row. On 12 July Maguire was awarded the 2018
Edith Cummings Munson Golf Award by the Women's Golf Coaches Association (WGCA) for the second year in a row. Amateurgolf.com selected her as the second best female amateur golfer of the last ten years.
Golfweek selected Maguire as the best women's college golfer of the last decade. ==Professional career==