The Ivory Coast international revealed last week that he had agreed terms on a new deal, and he put pen to paper on Monday.
Now Kalou is looking forward to at least another three years at Stamford Bridge, having committed his future to the club until 2012.
"I am delighted to stay here for the next three years so I can improve my game and play more games," he told skysports.com.
Best choiceKalou had been strongly linked with a move across the capital to rivals Arsenal, but he is happy to have stayed put.
"I heard a lot, there was some interest in me, but I think I made the best choice of signing a new contract here at the Bridge," he continued.
"Hopefully I can get more chances from the manager and play more to improve my game."
The signing of the new deal ends a very good few days for Kalou, who also helped Ivory Coast make the World Cup finals.
"I am happy with my week, we qualified for the World Cup and I sign a new contract with Chelsea, it is an excellent week for me," he concluded.