Northampton and Bishop's Stortford Morison joined
Northampton Town as part of the club's
youth system following a successful trial period, having also spent time on trial at
Leicester City. He made two further appearances for the club, scoring Northampton's equaliser away at
Darlington on 18 September 2004. The following month, Morison signed for
Conference South club
Bishop's Stortford for an undisclosed fee. He scored on his debut in a 1–1 draw against
Redbridge. He helped Bishop's Stortford reach the semi-final of the
FA Trophy and ended the season as both the club's top goalscorer and the 2004–05 FA Trophy leading goalscorer. In the following season, Morison initially struggled for form and was used primarily as a substitute during the first two months of the season. He returned to the starting line-up for a match against
Histon in November 2005, scoring a hat-trick in a 5–0 victory.
Stevenage Borough After opening the
2006–07 season by scoring two goals in two matches for Bishop's Stortford, Morison joined
Conference National club
Stevenage Borough on a two-year contract in August 2006 for a "small four figure fee". He scored on his debut in a 3–2 defeat against
Crawley Town on 19 August 2006, and followed this up with a
hat-trick against
Morecambe in a 3–3 draw at
Christie Park in the club's next fixture. Morison scored regularly during his debut season, contributing to the club's success in the
FA Trophy, where he finished as the competition's top goalscorer with eight goals. This included scoring the winning goal in the
final in May 2007 against
Kidderminster Harriers, as Stevenage overturned a 2–0 deficit to win 3–2 at
Wembley Stadium in front of a competition-record crowd of 53,262. Morison made 53 appearances during the season, scoring 34 times in all competitions and finishing as the club's leading goalscorer. as the club narrowly missed out on the Conference Premier play-offs. At the end of the season, Morison submitted a transfer request as he sought a return to
the Football League. Although the club accepted the request and received interest from
League Two club
Crewe Alexandra, no transfer materialised, and Morison subsequently signed a new three-year contract with Stevenage. The contract contained a clause allowing him to leave the club at the end of the
2008–09 season for a pre-agreed fee, should Stevenage fail to achieve promotion to the Football League. He scored 30 goals in 51 appearances for the Hertfordshire club during the 2008–09 season, and captained the team for the majority of the season. His season began with a 5–0 away defeat to
Wrexham, a match in which Morison was sent off for an "off-the-ball headbutt". He missed the following three games through suspension, but returned in early September 2008, scoring a hat-trick against eventual champions
Burton Albion and two goals against Altrincham in successive matches. Morison also scored seven times in seven games in the FA Trophy that season, including one in the 2–0 victory against York City in the
final on 9 May 2009. During his three-year spell at the club, Morison made 152 appearances and scored 89 goals. This tally ranks him as the
second-highest goalscorer in the club's history. Morison made his debut for
Millwall in the opening match of the
2009–10 season, starting in a 1–1 draw with
Southampton on 8 August 2009, during which he provided the assist for Millwall's equaliser. A month later, he scored his first goal for the club in a 3–1 victory against
Huddersfield Town. After scoring seven goals in five matches in March 2010, Morison was named
Football League One Player of the Month. He scored in Millwall's 2–0 win against Huddersfield Town on 18 May 2010, his 23rd goal of the season, as Millwall progressed to the League One play-off final, where they defeated Swindon Town 1–0 at
Wembley Stadium on 6 June 2010. The victory marked Morison's third successive win at the stadium. He scored 23 goals in 52 appearances during his debut season at Millwall leaders
QPR Morison began the
2010–11 season by assisting two of Millwall's goals in a 3–0 victory over
Bristol City at
Ashton Gate on 7 August 2010. In the club's following league match, he scored two headed goals as Millwall defeated
Hull City at
The Den. It was reported that Millwall rejected a £2 million offer for Morison from Nottingham Forest on 15 October 2010, with Millwall manager
Kenny Jackett stating there would be "no chance" that Morison will be sold in the
January transfer window. Morison subsequently signed a new -year contract with Millwall on 5 February 2011, ending transfer speculation regarding his long-term commitment to the club. Morison concluded the season having scored 17 goals in 43 appearances.
Norwich City At the end of the 2010–11 season, Morison submitted a
written transfer request amid speculation linking him to a move to newly promoted
Premier League club
Norwich City. Millwall rejected the request. Millwall subsequently accepted an offer from Norwich after the two clubs agreed a fee for the player on 2 June 2011. It was the fourth bid Norwich had submitted for Morison. He signed for the club on a three-year contract for an undisclosed fee on 6 June 2011. Morison made his Norwich City debut against
Wigan Athletic during the club's opening match of the
2011–12 season, playing 75 minutes in a 1–1 draw and providing the assist for Norwich's equalising goal. He scored his first goal for the club in Norwich's first home win of the season, a 2–1 victory over
Sunderland on 26 September 2011. He scored his 10th goal of the season in a 3–3 draw away to Arsenal at the
Emirates Stadium on 5 May 2012. Morison's late goal from a tight angle drew Norwich level after they had trailed 3–2 with five minutes remaining. The following season, under new Norwich manager
Chris Hughton, Morison featured predominantly as a substitute, starting only four matches during the first half of the 2012–13 season. He scored his first goal of the season in a 5–2 home defeat to
Liverpool on 29 September 2012, a match in which he was named in the starting line-up. Morison made his final appearance for Norwich in a 4–3 defeat to
Manchester City in the club's last match of 2012. He made 59 appearances during his one-and-a-half-year spell at the club, scoring 12 goals.
Leeds United On the final day of the
2013 January transfer window, Morison signed for Championship club
Leeds United as part of a swap deal. The transfer involved
Luciano Becchio moving to Norwich, with Norwich also paying Leeds a "further undisclosed sum". Upon Morison's arrival, Leeds manager
Neil Warnock stated: "Steve meets all the requirements of the striker we've been looking to bring in. For me, he is a player who has everything. He can score goals from anywhere, whether it's 25 yards or a tap-in, he has pace, and he has all the attributes you want". He scored his first goal for the club on his home debut on 20 February 2013, the second goal in a 2–0 victory over
Blackpool. He scored three goals in 16 appearances during the second half of the 2012–13 season. Upon his return, he stated: "I'm pleased to be back here. If anybody has any doubts about me all I'd say is that I aim to score plenty of goals for Millwall and help this club to greater success". Morison made 41 appearances during the loan agreement, of which 25 were starting, and scored eight times as Millwall finished 19th in the Championship. Morison missed the opening matches of the season through injury, making his first league appearance for Leeds in over a year as a substitute against Huddersfield Town on 20 September 2014. He scored his first goal for Leeds in more than two years with a volley in a 2–1 defeat to
Charlton Athletic on 19 April 2015. He made 26 appearances during the season, scoring twice. He scored in the first game upon returning, a 2–1 victory over
Shrewsbury Town on 8 August 2015. Morison scored 19 goals in 57 appearances during the season, as Millwall were defeated 3–1 in the
2016 Football League One play-off final on 29 May 2016. He made 50 appearances over the course of the season, scoring 19 times. He made his competitive debut for the club on 3 August 2019, starting in a 1–0 home victory against
Portsmouth. The loan agreement was made permanent on 8 August 2019 and was set to run until the end of the 2019–20 season. He made nine appearances for Shrewsbury during the opening months of the
2019–20 season. Morison announced his retirement from playing with immediate effect on 18 October 2019, in order to begin his coaching career at the academy of his first club, Northampton Town. ==International career==