The 31-year old striker has scored 42 goals in 138 appearances since he joined from Bolton Wanderers in 2008.
Speaking to the Blues' official website, he said: "When I first came to Chelsea I wanted to stay much longer than what I did in the past with other clubs.
"It is a big club, you play with big players and I like this club, I like London. There is no need to move anymore and so I am very glad to sign a new contract and I know we will play in big games and win titles. I am very glad."
Boss Carlo Ancelotti added: "Nicolas is a fantastic player who has good technical qualities and movement.