Mounié is a Montpellier youth academy graduate. He made his first team debut on 28 October 2014 in a 2014–15 Coupe de la Ligue round of 32 home match against AC Ajaccio, replacing Jean Deza after 86 minutes; Montpellier lost the match 1–0.[3]
On 31 August 2015, Mounié was loaned to Nîmes Olympique of Ligue 2 for the rest of the 2015–16 season.[4] He was the club's top scorer for the season, with 11 goals in 33 competitive matches, all of them scored during the league campaign.
On 29 June 2016, Mounié extended his contract with Montpellier by two years to 30 June 2019.[5]
On 11 March 2017, Mounié scored for the fifth consecutive Ligue 1 match in a 3–2 home loss to Nantes; it was his 13th league goal of the season.[6]
Huddersfield Town
On 5 July 2017, Mounié joined newly promoted Premier League club Huddersfield Town on a four-year deal for a club record fee of €13 million (£11.5 million) plus add-ons. The record fee surpassed the previous record £8 million (initial fee) that the club spent on Aaron Mooy from Manchester City a week earlier.[7]
Mounié made his competitive debut on 12 August 2017, scoring twice in Huddersfield's first match in the division, a 3–0 win at Crystal Palace.[8] On 11 February 2018, he scored, assisted Mooy and forced an own goal in a 4–1 home win over AFC Bournemouth.[9]