The north London side finished third last term as the Blues got back to winning ways in the top flight under the Portuguese coach.
But things could so easily have been different for Arsenal, believes the pundit, had they had Arsene Wenger's great rival at the helm.
Cascarino told Sky Sports: "The difference between Chelsea and their rivals is the manager. I believe that if Mourinho was manager of Arsenal, he’d have won the league. Likewise with Man City. That’s the quality he brings.
"John Terry said Petr Cech is worth 15 points. Maybe so. Mourinho is worth more than that to Chelsea."
Cascarino's statement is one designed to create debate, of course, but it's hard to disagree with him.
Never would it be easy to imagine Mourinho in charge of a side like Arsenal. If it ever happened, however, the Chelsea boss is better equipped than anyone to hit his targets in England and, ultimately, win titles.
While Arsenal fans criticise Mourinho for parking the bus, his sides entertained for large periods last term before putting the material aspects of the game to one side and adopting a pragmatic approach. It was a winning approach - and it's something Arsenal haven't had for many, many years in the Premier League.