In his eighth year at Chelsea, Ryan is a fast, attacking left-back, converted from a winger, who was signed in July 2005 from Gillingham. A tribunal set the fee at £125,000 initially with additional amounts to be paid depending on progress.
He signed professional in August 2006 and was taken on the first team pre-season visit to America in that summer.
Loans have dominated his career prior to his Chelsea debut with important first team experience gained.
League One Bournemouth was first in 2006/07 although Ryan missed the final two months of that season having suffered a ruptured spleen in a Chelsea reserve match.
He recovered to spend the rest of 2007 at League One Oldham and in January 2008 he moved up a division to Norwich where he spent 18 months, racking up 60 appearances, although the story ended on a down note with relegation.
Ryan spent the entirety of the 2009/10 season on loan at Reading, missing just two league games and then featured in Chelsea's pre-season fixtures for the first time since 2006. In early August 2010 he signed on loan at Nottingham Forest until the new year. He was a regular for the promotion-chasing Championship side, making 19 league starts. taking his Championship experience to over 150 matches.
From January 2011 onwards, and with Patrick van Aanholt going out on loan, Ryan remained at Chelsea to take over as Ashley Cole's understudy and made his debut as a sub in league game at home to Birmingham in April.
Andre Villas-Boas decided not to loan him out for the 2011/12 season, and he provided reliable backup to Ashley Cole over the course of the campaign, featuring heavily in the domestic cup competitions with displays of energy and pace.
As a gruelling schedule began to take its toll towards the end of the season, Bertrand was chosen to start crucial league games against Wigan Athletic, Fulham, Arsenal, Newcastle and Liverpool.
However, the highlight of his campaign, and arguably his career to date, came when he was selected for the Champions League Final against Bayern Munich on 19 May. Playing in an unfamiliar role further forward, the youngster impressed before being withdrawn midway through the second half due to a calf injury, but ended the biggest night of his life with a Champions League winners' medal.
He started the 2012/13 season in the same manner that he finished the previous one, with Roberto Di Matteo giving him the nod to start our first league game against Wigan, playing in a more advanced role, much like the Champions League final, and completing the full 90 minutes.
He scored his first Chelsea goal in the 3-2 FA Community Shield defeat against Manchester City at Villa Park, before signing a new, five-year contract a month later.
While Bertrand has, at times, filled in at left-back during the current campaign, he has been used more often on the left-hand side of the attacking trio tucked in behind the striker.
Used predominantly as a squad player during the current campaign, Bertrand was handed a sustained run in the side at left-back when Ashley Cole suffered a hamstring injury in an FA Cup replay against Manchester United.
The youngster had his first taste of Wembley action for the Blues when he played the full 90 minutes in the FA Cup semi-final against Manchester City, although he was unable to prevent us from suffering a 2-1 defeat.
Ryan made an England Under 19 debut in late 2006, and has since stepped up to be an England Under 21 regular, playing in last summer's European Championships in Denmark.
He made history in the summer of 2012 when he was chosen by Stuart Pearce to compete for Team GB at the London Olympics, playing in three of the four matches, and impressing to such an extent that he was called into the senior England squad by Roy Hodgson for a friendly against Italy in Switzerland.
Bertrand came on midway through the second half, replacing Leighton Baines, to make his England debut. With almost his first touch, he cleared an Italian header off the line, from which England launched a move which ended with Jermain Defoe scoring the decisive goal in a 2-1 win.
He made his competitive debut shortly after, coming on as a second half substitute in the 1-1 draw with Ukraine at Wembley.
Bertrand was a late call-up to the squad for the qualifiers against San Marino and Poland in October 2012, owing to an injury sustained by Kieran Gibbs, but the Blues left-back was struck down with illness and also had to withdraw from Roy Hodgson's squad ahead of the matches.