Chelsea says in a statement on Friday it is "the biggest deal to date Chelsea has signed with a partner," though no financial details were revealed.
Adidas has provided the Blues with their football kits since 2006.
"We are delighted to extend our partnership until 2023 after a highly successful first seven seasons. Both organisations share the same ethos and ambition and the new deal reaffirms Adidas' belief in the club's status in world football,' said Chelsea's chief executive Ron Gourlay.
"Both adidas and Chelsea have a long and proud heritage in football and we are delighted to continue our working relationship with one of Europe's elite football clubs. We look forward to many more years of success, working closely with the club on product, marketing and grassroots initiatives in the UK and around the globe," Herbert Hainer, CEO of Adidas AG added.