Varane played for French club Lens at youth level and, ahead of the 2010–11 season, began training with the senior team and appeared on the bench in several league matches.

He departed England in 2024, joining newly-promoted Serie A side Como as a free agent, but after just playing 23 minutes for the club, picked up a knee injury and was removed from the squad list, before subsequently announcing his retirement from professional football in September 2024.

In the 2008–09 season, alongside teammates Thorgan Hazard and Geoffrey Kondogbia, he played on the club's under-16 team that won the Championnat National des 16 ans.

[citation needed] In late October of the campaign, Varane was called up to the senior team by manager Jean-Guy Wallemme to train ahead of the club's match against Montpellier on 6 November.

He trained with the team for the entire week and, due to an injury to centre-back Alaeddine Yahia, Varane was, surprisingly, named to the starting line-up.

Varane was praised by teammates, most notably captain Adil Hermach, defensive partner Éric Chelle, and striker David Pollet, as well as by the local media and coach Wallemme.

[14][15] In the next two matches, Varane, alongside several other youth players, sat on the bench as Lens faced two tough teams in Marseille and Lyon.

In December, with both Chelle and Yahia returning to action, Varane was placed in the defensive midfielder role in the team's match against Bordeaux.

In the match, he acted as a roving third centre-back and made a blocked save in the 84th minute on a close range shot by Yoan Gouffran to preserve a 2–1 lead.

[citation needed] Varane made his competitive debut for Real Madrid on 21 September in the team's league match against Racing Santander.

[34] In the team's next league match three days later against Rayo Vallecano, Varane started and scored his first goal for the club after a flying back-heel shot following a Mesut Özil corner.

[35] On 27 September, he made his UEFA Champions League debut in a 3–0 group stage win over Dutch club Ajax.

In the return leg at the Camp Nou on 26 February 2013, Varane scored Madrid's third goal in a 3–1 away win with a header from a corner kick by Mesut Özil.

Varane gained praise from former World Cup winner Bixente Lizarazu after his performances against Barcelona and Manchester United.

Varane continued to impress in the Champions League quarter final first leg against Galatasaray, where he helped Madrid keep a clean sheet in a 3–0 triumph.

[citation needed] In April 2013, Varane was named by Marca readers as a member of the "Best foreign eleven in Real Madrid's history".

[40] Varane came on as an injury-time substitute for Karim Benzema in the 2014 Copa del Rey Final which Real Madrid won 2–1 against Barcelona on 16 April.

After the game, Atlético captain Gabi excused Varane due to his youth, while Simeone himself said, "I also made a mistake with my reaction.

[49] Following his club and international performances throughout the year, he was included in the 30-man shortlist for the 2018 Ballon d'Or,[50] finishing in seventh place in the final ranking.

The mistakes committed by the Frenchman were due to the high pressuring from Gabriel Jesus which led to Varane losing possession of the ball both times.

[59] On 27 July 2021, it was announced that Manchester United and Real Madrid had reached an agreement for Varane's transfer, subject to a medical and to player terms being finalised.

United manager Erik ten Hag said in a press conference on 26 October that the injury would rule Varane out of all of the club's matches ahead of the break for the 2022 FIFA World Cup, leaving his chances of being selected in the France squad for the tournament uncertain.

[70] On 25 May 2024, Varane made his final appearance for the Red Devils, lifting the FA Cup after a 2–1 victory against local rivals Manchester City at Wembley.

[71] On 28 July 2024, it was announced that Serie A club Como signed Varane on a two-year deal with an option to extend.

[86] On 15 June 2014, he partnered Mamadou Sakho in central defence for Les Bleus' first World Cup fixture – a 3–0 win over Honduras.

[90] On 14 October, Varane became the youngest player to captain France when he took over from Blaise Matuidi at half time in a 3–0 win over Armenia.

[91] He was then selected as the team's starting captain for a home friendly against Sweden on 18 November, where he scored his first international goal to give Les Bleus a 1–0 win.

[98] On 18 December, Varane was named in the starting line-up for France as they played their second successive World Cup final, eventually losing 4–2 on penalties to Argentina.

Varane was described by Lens youth coach Éric Assadourian as a "truly first-class player" who was "comfortable on both the tactical and technical level.

"[103] Varane's height made him effective in the air, while his confidence on the ball allowed him to evade the opposing team's press and start attacking plays from the back with his passing.