Kenyon told the Evening Standard: "There's no question that Jose is capable of matching Sir Alex's achievements. He joined us because he shares our vision of making Chelsea a top European club. That's what excited him and that's why he's here."
Claudio Ranieri was sacked for failing to win a trophy last season but Mourinho will be given at least two years to prove himself at Chelsea.
Kenyon added: "There's no demand that we succeed this season and we're interested in sustainable success."
Failure on the pitch could well see Kenyon out the door before Mourinho.