Kezman, who joins former PSV Eindhoven team mate Arjen Robben at Stamford Bridge, signed a four-year deal.
Chelsea and PSV agreed a transfer fee, which was not disclosed, earlier this month.
"I'm very glad that I'm here, it's a fantastic club with a great history and has a good team," Kezman told Chelsea's website.
The 25-year-old, who joined PSV from Partizan Belgrade in 2000, was top scorer with 31 goals in the Dutch first division last season.
"I've got the best record in the history of the club (PSV). I just need some time and (Chelsea's) supporters need to be patient, but I'm sure it'll be okay," he said.
