Kalou is in his fourth year at Stamford Bridge and has made 93 starts, 66 substitute appearances and scored 31 goals for the club.
Blues boss Carlo Ancelotti predicted a bright future for the striker, who has followed Didier Drogba, John Terry, Ashley Cole, John Mikel Obi, Florent Malouda, Hilario and Michael Mancienne in extending his stay in west London.
"I am very pleased that Salomon has signed a new contract with us as he is an important player for this club," said Ancelotti. "He is always well motivated and works hard at his game at all times. Because of this I am sure that Salomon will become an even more important player for Chelsea in the future."
Chelsea had allowed Kalou to come within eight months of becoming a free agent, suggesting the club's commitment to keeping him was not as great as Ancelotti's comments imply.
The bargaining power of players on the current staff has however been increased by the fact that Chelsea are banned from signing any new players until January 2010 as a result of being found guilty of inducing teenager Gael Kakuta to breach his contract with Lens two years ago.
According to English media reports, Kalou's new deal gives him a salary of £60,000 a week.