The Spain international left Camp Nou for around £30m, and Pique thinks that the switch to Stamford Bridge has worked out well for his former teammate.
He told The Guardian: "He is really happy there, and playing well. He loves London, even if I don't know if he loves [Chelsea manager] Jose Mourinho.
"He probably does because he is in the team, playing all the games. In Barcelona it was more difficult for him. It was one of the toughest decisions in his life to leave Barca for a second time but, after three months, you can see he made the right decision.
"He's enjoying his life, playing every minute. He doesn't like to be rotated, and I'm happy for him."