Zouma began his career at Saint-Étienne, making his professional debut aged 16, and going on to win the Coupe de la Ligue with the club in 2013.

After loan spells with Stoke City and Everton, he moved to across London to West Ham in 2021, winning the UEFA Conference League in his second season.

[6] He was subsequently promoted to the senior team by manager Christophe Galtier ahead of the 2011–12 season, and initially played without a name on his shirt in order to protect him from media attention.

[8] On 17 September, he made his Ligue 1 debut in a 3–0 loss at Lorient; his first professional goal came on 19 November, replacing Paulão after nine minutes and finishing a corner kick to confirm a 2–0 win before half time at OGC Nice.

[11] Eight days later in the Derby du Rhone away to Lyon, he opened a 1–1 draw by heading Yohan Mollo's corner after half an hour of play.

[12] On 7 November 2013, Zouma was banned for ten games following a challenge that left Sochaux's Thomas Guerbert with a broken right leg and a dislocated ankle.

[14] On 24 September, Zouma made his first competitive appearance for Chelsea, scoring the opener in a 2–1 win against Bolton Wanderers in the third round of the League Cup.

[15] He made his second Chelsea start and first UEFA Champions League appearance on 21 October against Maribor, helping his team keep a clean sheet in a 6–0 win.

[19] With Nemanja Matić suspended and Mikel John Obi injured, Zouma played in defensive midfield as Chelsea won the League Cup Final on 1 March after a 2–0 victory over Tottenham Hotspur.

[20] On 3 May, he featured as a substitute for the final five minutes in place of Willian as Chelsea defeated Crystal Palace 1–0 to win the league title.

[22] Starting ahead of John Terry, he scored his first Premier League goal on 19 September, heading in Cesc Fàbregas' cross to open a 2–0 home win over the same opposition.

[23] On 24 November, as a late substitute for the injured Terry, he scored his first European goal to conclude a 4–0 win at Maccabi Tel Aviv in the Champions League group stage.

On 7 February 2016, Zouma ruptured the anterior cruciate ligament in his right knee after landing awkwardly from a jump in a match against Manchester United.

[27] On 24 October, Zouma made his first competitive appearance after being out of action for nine months, playing 45 minutes for the Chelsea under-23 team in a 2–2 draw against Derby County.

[30] Following agreeing to a new six-year contract with Chelsea, on 21 July 2017, Zouma joined fellow Premier League club Stoke City on loan for the 2017–18 season.

[33] In November 2017, Stoke captain Ryan Shawcross expressed his surprise that Chelsea had loaned out Zouma, who had only missed one match, against his parent club.

[56] The appointment was criticised by The Times journalist, Henry Winter who wrote "James Ward-Prowse is more deserving because he’s a natural captain and he’s never kicked a cat.

[62] Senior France manager Didier Deschamps wanted to build a defence around Zouma and fellow youngster Raphaël Varane,[7] and on 19 March 2015, he was called him up for the first time for friendlies against Brazil and Denmark.

[63] He made his debut in the latter match ten days later, a 2–0 win at his former club ground with Saint-Étienne, the Stade Geoffroy-Guichard, replacing Morgan Schneiderlin for the last eight minutes of the game.

[68][69] A November 2013 report by FourFourTwo noted Zouma's strength, reading of the game, and aerial presence, while mentioning his occasional lapses in concentration.

"[70] In February 2015, Match of the Day pundit Danny Murphy likened Zouma to Marcel Desailly, another Frenchman who played in defence for Chelsea.

[88] On 10 February, National League club Dagenham & Redbridge suspended Yoan Zouma for filming the abuse of the cat.

[88] On 16 March 2022, the RSPCA announced that after a full investigation they had started the process of bringing a prosecution against Kurt and Yoan Zouma under the 2006 Animal Welfare Act.

[93] In 2024 football agent, Saif Alrubie appeared at Southwark Crown Court charged with sending an electronic communication with intent to cause distress or anxiety to Chelsea director, Marina Granovskaia.