One Day and Twenty20 Debut During the 2006–07 Australian summer, Duffin was selected for the national youth team to play against New Zealand A, where she had more success as a
leg spinner than as a batter. In the final match of the series, she took 6/28 in a 22-run defeat. At the start of the 2008–09 season, Duffin played for an under-21 Australian team in a series against
India. She made 60 of the team's 149
all out total in the second-last match, then delivered an
unbeaten 79 in the team's winning score of 5/156. On 15 February, Duffin made her
T20 International debut at the
Sydney Cricket Ground, also against New Zealand. She was not required to bat or bowl in a rain-shortened match that Australia won by nine wickets. Duffin was selected in Australia's squad for the
2009 Women's Cricket World Cup on home soil. She played six of a possible seven matches and scored 81 runs at an
average of 16.20, with the hosts finishing in fourth place. Duffin was then selected for the
2009 World Twenty20 in
England. She only played one game and Australia were eliminated in the semi-finals.
Solidifying position, makeshift wicket-keeper In the middle of the 2009–10 season, Duffin played for the Australian Under-21s against the New Zealand Emerging XI. She compiled 128 runs at 42.66 in five matches, with a best score of 66 in the fourth fixture. She was not required to bat in the last two matches and finished the series with four dismissals behind the stumps. This experiment was only repeated once more, with Duffin going on to settle as a top-order batter for the team.
2010 World Twenty20 triumph Duffin was selected for the
2010 World Twenty20 in the
West Indies, playing every game of Australia's unbeaten run. In the first match against
England, both teams finished their respective innings with a score of 104. The deadlock could not be broken in the resulting
super over, with the match having to be decided by a count back on the number of
sixes scored. The only six of the game had been hit by Duffin which ultimately secured victory for Australia. In a low-scoring final against New Zealand, Duffin put on a 30-run partnership with
Leah Poulton to help Australia win by three runs and claim their maiden World Twenty20 championship.
Test debut and second-straight World Twenty20 title On 22 January 2011, Duffin made her
Test cricket debut at
Bankstown Oval against England. She scored 30 runs from 71 balls in the second innings of the match and Australia went on to win by seven wickets. In an ODI against
India on 16 March 2012 at
Wankhede Stadium, Duffin recorded her highest score at international level, making 90 not out off 87 balls which steered Australia to a five-wicket win. At the
2012 World Twenty20 in
Sri Lanka, Duffin was the tournament's second-highest run-scorer. In a group stage encounter with
Pakistan, she was named Player of the Match for her innings of 42 off 28 in a 35-run win (via the
Duckworth–Lewis method). In the championship decider against England, Duffin scored 45 off 34 to help the team post a first innings score of 4/142. She was named Player of the Final in a four-run victory as Australia claimed their second-consecutive title.
2013 Cricket World Cup At the
2013 Cricket World Cup in
India, Duffin put on a 182-run stand with
Meg Lanning during a group stage match against New Zealand. Her innings of 82 off 87 helped Australia chase down a target of 228 with seven wickets and 70 balls remaining. In the final against the
West Indies, Duffin scored 75 off 76 in a first innings total of 7/259. She was named Player of the Match while Australia won by 114 runs to earn their sixth 50-over World Cup. On 11 August 2013, Duffin recorded her maiden Test half-
century during a
drawn Women's Ashes match at the
Sir Paul Getty's Ground. She was dismissed without scoring another run in the first innings before making 24 in the third innings.
Third-consecutive World Twenty20 title Duffin's best performance at the
2014 World Twenty20, held in
Bangladesh, came against
South Africa when she scored 27 not out off 24 deliveries and put on an unbeaten 60-run stand with
Ellyse Perry. Coming together with Australia in trouble at 4/56 in the twelfth over, the pair turned the match around to guide their team over the line with eight balls to spare. In the final against England, Duffin (despite not facing a ball) and Perry were once again the batters at the crease when the winning runs were scored. Australia sealed victory with six wickets and 29 balls remaining to win their third-straight World T20 title.
Break and potential comeback In June 2015, Duffin was selected in Australia's touring party for the successful
2015 Women's Ashes campaign in England. Her most notable contribution of the series came in a T20I at the
County Ground in Hove when she scored 21 not out to help secure a 20-run victory which regained the Ashes for Australia. It was, as of June 2020, her last international cricket tour. In October 2015, Duffin announced she would be taking an indefinite break from pursuing her international career. In December 2019, during and after an outstanding
WBBL|05 season, media speculation mounted around Duffin's potential recall to the national team ahead of the
2020 Women's T20 World Cup. However, she declined to participate in an upcoming Australia A series against India A, which some outlets interpreted to mean she had chosen to prioritise her
AFL Women's career. In actuality, she had decided to prioritise starting a family with her husband Chris, announcing on 31 December she would halt her dual-sporting commitments to give birth to the couple's first child. ==Domestic cricket==