The France international completed his £30 million move from Leicester City on Saturday as he became Conte's second signing since arriving in west London.
The former Caen midfielder has thanked Leicester and their supporters for giving him a chance in the Premier League before hailing the project Conte is attempting to create at Chelsea.
"This season I discovered the Premier League championship with FC Leicester," he wrote in a statement on Twitter. "I want to thank the leaders, my team-mates and Claudio Ranieri for this fantastic season that saw us winning the title of England.
"Their confidence and also the fans' will forever remain in my memory. And I again thank you all.
"The club's project and the coach's speech have convinced me to join this new ambitious adventure."