Cech will perform an intermediary role between the club's new manager and director Marina Granovskaia, which had been left vacant since two years ago.
"Petr Cech returns to Chelsea as Technical and Performance Advisor," said Chelsea in a statement.
"His new role in Chelsea is to provide advice on all football and performance matters throughout the club as well as ensuring that the various support departments of the football academy are working together effectively."
Cech won 13 major honours, including four Premier League titles and the Champions League, in a stellar 11-year career with Chelsea before joining Arsenal in 2015.
The former Czech international's final game before retirement came in a 4-1 defeat by Chelsea as the Blues lifted the Europa League in May.
"I feel very privileged to have this opportunity to join Chelsea FC again and help create the best possible high level performance environment to continue the success the club has had over the past 15 years," he said.
"I'm looking forward to the new challenge and hope I can use all of my football knowledge and experience to help the team achieve even more success in the future."