Chalobah joined Chelsea at the age of eight and progressed through the club's academy. He spent time out on loan with Ipswich Town, Huddersfield Town and French side Lorient. He made his senior debut for Chelsea in the 2021 UEFA Super Cup, helping the club lift the trophy following a penalty shoot-out win.
He has represented England at various youth levels from under-16 to under-21 level. In 2017, he helped England win the 2017 UEFA European Under-19 Championship.
He signed for Championship club Ipswich Town on a season-long loan deal in June 2018.[14] He made his professional debut on 4 August, starting in a 2–2 draw with Blackburn Rovers.[15] Two weeks later he scored his first senior goal, equalising in a 1–1 draw with Aston Villa at Portman Road.[16] On 6 October, he scored a late winner in a 3–2 win against Swansea City, earning Ipswich their first league win of the season.[17] Despite primarily playing as a centre-back during his time in the Chelsea academy, he played as a central midfielder for Ipswich during his first season in senior football. Chalobah featured regularly for Ipswich during the 2018–19 season, playing 44 matches and scoring two goals for the team, who were relegated to League One.[18]
On 8 August 2019, Chalobah signed a new contract with Chelsea through to the 2022 season, and began a season-long loan at Huddersfield Town.[19] He made his debut five days later in a 1–0 home loss to Lincoln City in the first round of the EFL Cup, playing the full 90 minutes.[20] He scored his first goal for Huddersfield on 21 August against Cardiff City, initially equalising to level the score at 1–1, in a match that Huddersfield went on to lose 2–1.[21] He made 38 appearances in all competitions for Huddersfield during the season, scoring once.[22]
On 18 August 2020, Chalobah signed a new contract with Chelsea until 2023 and joined French side Lorient on loan for the 2020–21 season.[23] He made his league debut as a substitute on 13 September, in a 3–2 loss against RC Lens.[24] He scored his first goal for Lorient on 27 January, netting the opening goal in a 3–2 win against Dijon. Chalobah had another productive loan spell at Lorient, scoring 2 goals in 30 appearances, including scoring on the final day of the season in a 1–1 draw against Strasbourg.[25]
2021–2024: Return to Chelsea
On 11 August 2021, Chalobah made his debut for Chelsea in the 2021 UEFA Super Cup against Villarreal,[26] as his side won 6–5 in a penalty shoot-out after the match finished in a 1–1 draw after extra time.[27] Three days later, Chalobah made his Premier League debut in Chelsea's opening match of the season against Crystal Palace, in which he also scored his first Premier League goal in a 3–0 win.[28] On 4 November, Chalobah signed a new contract with Chelsea, keeping him at the club until 2026.[8] On 23 November, Chalobah scored his first UEFA Champions League goal, with the opener in a 4–0 home win against Juventus.[29]
On 29 October 2022, Chalobah scored an own goal in Chelsea's 4–1 defeat away to Brighton & Hove Albion in the Premier League. This was the first defeat in Chalobah's Chelsea career.[30]
Loan to Crystal Palace
On 30 August 2024, Chalobah joined Crystal Palace on a season-long loan.[31]