Petr Cech says he feels "very privileged" to be back at Chelsea, as the Blues explained just what his new role as Technical and Performance Advisor will entail.
The club's former goalkeeper returns after retiring as a player last month, with his final game coming for Arsenal against the Blues in the Europa League final in Baku, which Chelsea won 4-1.
Chelsea said in a statement: "The focus of the job will be to provide advice on all football and performance matters throughout the club as well as embed and facilitate strong links between our men’s and academy teams, ensuring that the various support departments are working together effectively.
Cech played 494 times for Chelsea, winning 13 major honours including four Premier League titles and the 2012 Champions League.
He moved across London to join Arsenal in 2015, picking up the FA Cup two years later.
"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," said Cech.
"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."
Club director Marina Granovskaia added: "We are delighted to welcome Petr back home to Chelsea.
"During his playing career here he was one of the most dedicated, successful and thoughtful professionals we have ever had.
"We always hoped that when Petr was ready to retire we would see him back at Chelsea FC and we are thrilled to add his expertise and knowledge of the game to the technical staff."