Born in Vannes, Brittany, Kermorgant began his career with the Stade Rennais Youth Academy, but aged 14 he was the victim of leukemia, and his career was halted for four years. He was signed for Vannes after initially playing at district-level but impressed the manager on trial. He spent two seasons at Vannes before joining Châtellerault for the 2004–05 season. He scored an impressive 14 league goals and was consequently signed by Grenoble. After two full seasons with Grenoble having scored 16 goals, he signed for Stade Reimsin the summer of 2007. When new manager Luis Fernandez took charge in January 2009, he made Kermorgant the captain. He finished the season with a total of nine goals and nine assists.
Kermorgant became a free agent after leaving Stade Reims at the end of the 2008–09 season. He entered talks with Championship team Leicester City in July 2009, and was given a trial by the club. Kermorgant was given a second trial after impressing in his initial display. On 24 August 2009, Leicester signed Kermorgant on a short-term contract until January 2010, beating French club Stade Malherbe Caen for his signature. He made his debut a day later as a 79th minute substitute in a 2–1 League Cup defeat to Preston North End. On 17 December, Kermorgant signed a two-and-a-half-year deal with Leicester, which would last until the end of June 2012. He made his first assist in a 2–1 FA Cup win over Swansea on 2 January 2010. Feeling the pressure of expectations since arriving, Kermorgant admitted at the end of January that he was still adjusting to life in England. He finally scored his first competitive goal for Leicester, in his 23rd game, in a 2–0 win over Middlesbrough on 2 May 2010. Kermorgant missed a penalty kick in a 4–3 defeat on penalties to Cardiff City in the Championship play-offs semi-final second leg on 12 May 2010. Kermorgant chipped his penalty, which was easily saved by Cardiff keeper David Marshall. On 23 July 2010, Kermorgant signed for Ligue 1 club AC Arles-Avignon on loan for the rest of the 2010–11 season. He was told he was free to look for a new club on his return to Leicester in August 2011.
On 13 September 2011, Kermorgant signed a two-year contract at Charlton Athletic, linking back up with his former first team coach at Leicester, Chris Powell. On 27 September 2011, he scored his first goal for the club in the away 1–1 draw with MK Dons. He then continued as the preferred striker to partner Bradley Wright-Phillips, and his impressive aerial ability and consistent performances attracted interest from Celtic in January 2012. Kermorgant won the League 1 title with Charlton Athletic on 5 May 2012, rounding off the season with a goal from an acute angle in a 3–2 victory against Hartlepool. He established himself as a fan favourite. On 25 July 2012, Kermorgant signed a new contract with Charlton Athletic, keeping him at the club until at least 2014 with an option for a further 12 months. He scored his first Championship goal for Charlton against his former club Leicester in which Charlton ran out 2–1 winners at The Valley. He repeated this feat, scoring in the reverse fixture at the King Power Stadium in which Charlton also won 2–1. Kermorgant finished the season with an impressive double against Bristol City, finishing the year as joint top goalscorer shared with Johnnie Jackson with 12 league goals. Kermorgant scored his first goal of the 2013/14 season on the first day of the season, scoring an acrobatic effort against Bournemouth. He once again scored against his former club Leicester along with Michael Morrison who also played for Leicester. The game finished in a 2–1 home win for the Addicks.
Bournemouth
On transfer deadline day 31 January 2014, Kermorgant signed for Bournemouth on a two-and-a-half-year deal for an undisclosed fee. He made his debut as a second-half substitute against former club Leicester City. On 1 March 2014, Kermorgant celebrated his full debut for Bournemouth by scoring his first goal for the club and his first ever hat-trick in a 5–0 win against Doncaster Rovers. In Kermorgant's first full season at Dean Court he helped them claim the Championship title winning promotion to the Premier Leaguefor the first time in the club's history. Kermorgant scored 17 goals in all competitions and was nominated for the Championship goal of the season award for a bicycle kick in the 2–2 draw against Ipswich Town.
On 20 January 2016, Kermorgant signed a one-and-a-half-year deal with Reading. On 2 January 2017, Kermorgant scored twice in Reading's 3–2 away win over Bristol City, including the 93rd minute winner, with Reading being 2–0 down in the 70th minute. On 10 February 2017, Kermorgant signed a new one-year extension to his contract, keeping him at Reading until the summer of 2018. On 1 November 2017, Reading announced that Kermorgant had put off his retirement plans at the end of the season to sign a new contract with the club until the summer of 2019. Reading announced on 10 July 2018 that Kermorgant's last year of his contract had been terminated by mutual consent.
Return to France
After training with Vannes OC since the start of the 2018–19 season, Kermorgant signed a contract with the French Championnat National 2 club on 2 October 2018. He announced his retirement on 22 April 2020.
International career
Kermorgant was named as part of the Brittany national football team squad ahead of their friendly against FIFA members Mali on the 28 May 2013. He started the game on the bench but was substituted on in the 62nd minute of the match, with the score still 0–0. After just 9 minutes on the pitch, Kermorgant scored in the 71st minute which beat goalkeeper Soumbeïla Diakité in the Mali goal. It was to be the only goal of the game, with the match ending in a 1–0 win for Brittany.
