Early career Mwepu's career began with
Kafue Celtic in Lusaka before being identified with the 2013 Airtel Rising Stars. During the 2015–16 season, Mwepu had little game time with Power Dynamos football club of Copperbelt; this precipitated into a move to
NAPSA Stars at the end of the 2017 season.
Red Bull Salzburg and loan to FC Liefering In June 2017, Mwepu joined
Red Bull Salzburg and was loaned out to Salzburg's feeder club
FC Liefering who play in
Austrian Football First League. On 18 December 2019, Mwepu extended his contract with Salzburg until summer 2024.
Brighton & Hove Albion On 6 July 2021, he joined
Premier League side
Brighton & Hove Albion on a four-year contract, for an undisclosed fee. He scored in a 3–1 pre-season friendly win at
Luton Town on 31 July. He made his competitive debut on 14 August in the opening game of the
2021–22 season away at
Burnley where he was replaced by
Adam Lallana at half time of the 2–1 victory at
Turf Moor. On 24 August, Mwepu assisted
Jakub Moder's first Albion goal in the
second round EFL Cup away fixture at
Cardiff City where Albion won 2–0. He scored his first goal for Brighton on 27 October, putting them back level to 2–2 before a penalty shootout loss – in which his penalty was saved – away at
Leicester City in the EFL Cup. Three days later, he scored his first league goal for the Sussex side, inspiring Brighton's comeback with a stunning 25–yard strike in a 2–2 away draw against
Liverpool. Mwepu had a slow start to 2022 and in general to his time in Sussex due to injury and illness, thus had limited playing time. On his first start since his return from injury Mwepu scored and made an assist for Trossard's opener in the 2–1 away win at
Arsenal on 9 April, to help Brighton end their seven-match run without a victory.
Graham Potter spoke that Mwepu has a "slight injury in his groin which probably means that will be him for the rest of the season," after picking up the knock during the 3–0 away victory at
Wolverhampton Wanderers on 30 April. His debut season with the "Seagulls" was marred by injuries though he had made a positive impact and at the club's end of season awards Mwepu won Goal of the Season for his strike at Liverpool in October. Mwepu managed to recover in time to appear as a substitute in the last game of the season, a 3–1 home victory over
West Ham United, with Brighton achieving their highest top flight finish in ninth place. On 10 October 2022, Mwepu retired from professional football at the age of 24 after being diagnosed with a rare hereditary heart condition. ==International career==