Chelsea have signed a 15-year kit deal with Nike worth £60m a season.
Adidas was paying Chelsea £30m a season, but it will be replaced by Nike from next season.
In May, Chelsea told Adidas they would be terminating their deal six years early in 2017. The west London club paid Adidas a £40m fee in order to curtail the agreement.
Chelsea wanted to leave Adidas because the club were unhappy that they were receiving less than half of the £75m per year that Manchester United were receiving from the German multinational.
Adidas and Nike are both believed to be in negotiations with Real Madrid about a world-record kit deal that would be worth more than £100m a year.