Full-back Bertrand was only a year into a four-year deal agreed last summer but has been rewarded for his remarkable progress in recent months.
The 23-year-old became the first man ever to make his Champions League debut in the final itself in May and made his England debut in last month's friendly win over Italy.
He has also started two of Chelsea's three Barclays Premier League games this season.
Prior to Roberto Di Matteo's appointment as manager in March, he barely figured for his parent club since making a controversial move from Gillingham seven years ago.
Ashley Cole's arrival as Chelsea's undisputed first-choice left-back saw Bertrand spend much of his early Stamford Bridge career out on loan.
He did not make his debut until April last year and there had been speculation he may be forced to leave in search of regular first-team football. But he is now very much seen as the heir apparent to Cole, whose own contract expires next summer.
He could also succeed Cole in the England set-up but will probably play second fiddle to Leighton Baines in Friday's opening World Cup qualifier in Moldova - Cole has been ruled out of that match through injury.
Former England Under-21 star Bertrand's elevation to the senior squad by manager Roy Hodgson is a reward both for his Chelsea displays and those for Great Britain at the Olympics.
Reports suggest Bertrand, who has been deployed in midfield much of the time by Di Matteo, has earned a pay rise to ?35,000 a week.
Source: PA
Source: PA