In 2009, at the age of seventeen, she joined
Le Mans FC for four seasons. During her time there, she contributed to the promotion to
Division 1 Féminine in the 2009–2010 season, finishing as
D2 champion. However, the following year, at the end of the
2010–2011 season, the club was relegated back to D2. Following her signing with
FF Yzeure Allier Auvergne in 2013, she played in the
2013–14 Division 1 Féminine. 2014 also saw her return to the Parisian suburbs where she played two seasons with Tremblay FC in D2. after two seasons in the club she moved to Division 2 side
FC Rouen for three seasons. In 2019,
Le Harve AC announced the signing of Koui for the 2019–20 season. where the contract was later renewed till 2022. Afterward, she joined Division 2's club
FC Nantes. Playing for Nantes for two seasons, she contributed the club's historic promotion to the
Première Ligue. Her brace on the final matchday against
ASPTT Albi was crucial in securing their historic promotion. On 27 May 2024, Koui announced her retirement from professional football after achieving promotion to Première Ligue with the club. ==International career==