In May 2012, Bertrand became the first player to make his Champions League debut in the final, starting in an unfamiliar left wing role in front of Cole; Chelsea beat Bayern Munich 4–3 on penalties.

[7] Bertrand was signed by Chelsea in July 2005 from Gillingham for an initial £125,000, which was set by a tribunal and was subject to increases depending on progress.

[13] On 4 January 2008, a matter of days after his spell at Oldham came to an end, Bertrand joined Norwich City on loan for the rest of the 2007–08 season.

[24] Bertrand made his Premier League debut on 20 April 2011, when he came on as substitute to replace Ashley Cole in a 3–1 win against Birmingham City.

[25] Bertrand also made a goal, providing a cross which Florent Malouda headed past Birmingham goalkeeper Ben Foster.

[31] He made his first league appearance of the season coming on as a late substitute for Ashley Cole against Everton, the match ended in a 2–0 defeat for Chelsea.

[32] Bertrand was handed his first Premier League start against Wigan Athletic on 7 April, in which he produced an outstanding performance, as Chelsea won 2–1 and he was named fan's man of the match.

[38] On 25 September, he scored his second professional goal in a League Cup match against Wolverhampton Wanderers at Stamford Bridge, which Chelsea won 6–0.

[41] He started the next match, the Europa League quarter-final first leg against Rubin Kazan at Stamford Bridge, putting in a strong performance as Chelsea ran out 3–1 winners.

[43] He started at left-back in the FA Cup semi-final against Manchester City at Wembley Stadium on 14 April, which ended in a 2–1 defeat for Chelsea.

[44] In the continued absence of Ashley Cole, Bertrand started and performed well in the next league match in the West London derby against Fulham at Craven Cottage on 17 April, which Chelsea comfortably won 3–0 thanks to a 30-yard strike from David Luiz and a brace from John Terry.

[48] He made his competitive debut for the club on 17 August in their first match of the league season, playing the full 90 minutes of a 2–1 defeat away to Liverpool.

[52] On 2 February 2015, Bertrand completed a permanent move to Southampton, signing a 4+1⁄2-year deal for an undisclosed fee,[53] reported to be £10 million.

[58] On 15 July 2021, Bertrand joined Premier League club Leicester City on a free transfer, signing a two-year contract.

[59][60] Bertrand made his debut for the club in Leicester's 1–0 triumph over reigning Premier League champions Manchester City in the Community Shield on 7 August 2021.

[citation needed] On 14 November, Stuart Pearce selected him at left-back for an under-21 match against Portugal at Wembley in Group 9 of the qualification process,[64] and helped the team keep first clean sheet since 29 June 2009.

[73] On 11 September 2012, Bertrand came on after 73 minutes in the 2014 FIFA World Cup qualification match against Ukraine and crossed the ball that led to the penalty that Frank Lampard converted.

"[81] In a 2018 ESPN FC article about the state of left-backs in England, Michael Cox said that the "only real star is Ryan Bertrand, a truly excellent full-back defensively and offensively".