The deal includes the rights to official kit and merchandise and other promotional opportunities on pitch-side LED hoardings and in the match programme.
Chelsea would not give a specific figure for the deal, only confirming that the deal was "multi-million" and that it had been significantly increased from its original deal.
The relationship was launched in 2006 when both parties created the world's largest team photo as 8,000 Chelsea fans lined up alongside the first team squad.
Chelsea and Adidas have since undertaken a number of grassroots projects, which has included partnering with youth football clubs in the US to help develop soccer in the country.
Ron Gourlay, Chelsea Football Club's chief executive, said: "Both organisations are highly ambitious and want to continue in partnership to develop globally and for us, grow in our key market territories across Asia and North America.
"[The] deal reaffirms Adidas' belief in the club's growing status in world football."
Herbert Hainer, chief executive officer of Adidas, said: "Both Adidas and Chelsea have a long and proud heritage in football and we're 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 grass roots initiatives in the UK and around the globe."