In 2001, the west London club signed a further 10-year deal with Umbro which was worth around £50million.
The contract will now end in June 2006, five years ahead of the original date.
Umbro will continue to be the kit-maker during the club's centenary season in 2005-6 when a new home kit and celebration products will be launched for the occasion.
A statement from Umbro said: "The company will receive a payment for early termination from Chelsea of £24.5m in June 2006 for the five-year period to 2011."
Kenyon said: "Umbro have made a major contribution to the Chelsea of today. However we believe this decision will help us achieve our strategic long-term goals."
Chelsea are top of the Premiership by 10 points and in the last 16 of the Champions League. They are also in the semi-finals of the Carling Cup and the FA Cup fourth round.