Le Mans Ahead of the
2012–13 season, Sanson was promoted to the senior team by
manager Denis Zanko and assigned the number 25 shirt. He made his professional debut on 3 August 2012 in a league match against
Dijon, replacing
Idrissa Sylla with only ten minutes to play. He scored his first league goal on 22 December 2012 against
Monaco in a 2–3 home loss.
Montpellier On 12 June 2013, Sanson signed a four-year contract with
Montpellier for a reported fee of €700,000. He made his debut for the club on 14 September 2013, in a 0–0 draw against
Stade de Reims.
Marseille in 2018 On 17 January 2017, Sanson joined south coast rivals
Marseille by signing a four-and-a-half-year contract, for an initial fee estimated to be €9 million, plus €3 million in bonuses. On 5 March 2017, he scored a goal in the 56th minute in a 4–1 Ligue 1 away win against
Lorient, his first Ligue 1 goal for Marseille. On 3 May 2018, he played in the
Europa League semi-finals away to
FC Red Bull Salzburg as Marseille played out a 1–2 away loss but a 3–2 aggregate win to secure a place in the
2018 UEFA Europa League Final which was played at the
Parc Olympique Lyonnais, and saw his team lose to
Atlético Madrid.
Aston Villa On 26 January 2021, Sanson signed for English
Premier League side
Aston Villa on a -year contract, for a fee believed to be £14 million, with £1.5 million in add-ons. On 3 February 2021, Sanson made his Aston Villa debut as a late substitute in a 3–1 defeat to
West Ham at
Villa Park. On 4 April 2021, Sanson suffered a knee injury midway through the second half in a 3–1 victory over
Fulham which ended his season prematurely. On 31 August 2021, Sanson made his return from injury as one of the permitted overage players for Aston Villa U21s, in a 3–1 victory over
Wycombe Wanderers in the
EFL Trophy. On 22 September 2021, Sanson returned to the first team in an
EFL Cup tie against
Chelsea – but he was forced to leave the field before half time after a recurrence of his injury. The arrival of
Steven Gerrard as Aston Villa manager coincided with Sanson regaining fitness and he started in the Premier League for the first time in 8 months on 26 December 2021. Gerrard described how Sanson had been disappointed with the start to his English football career, but he had assured him that he was aware of his talent, despite Sanson's fleeting appearances up until that point. In newly appointed manager
Unai Emery's first match for Villa, on 6 November 2022, Sanson made his first appearance of the 2022–23 campaign, coming on as a substitute in the 90th minute as Villa defeated Manchester United 3–1. On 8 January 2023, Sanson scored his first goal for Aston Villa in a 2–1 defeat to lower league
Stevenage in the
FA Cup.
Strasbourg loan On 23 January 2023, Sanson joined
Strasbourg on loan until the end of the current season.
Nice On 24 July 2023, Sanson joined
OGC Nice on a season-long loan. On 15 May 2024, it was announced that Nice had made the loan transfer a permanent one. ==International career==