Having spent nine years with the Blues, Cech knows only too well how quickly things can change at the club under the ownership of Roman Abramovich.
Mourinho has returned for a second spell in charge and spoke repeatedly at his unveiling last month of a desire for continuity.
|66/1||Jose Mourinho is 66/1 with Coral to be the first Premier League manager to be sacked
Cech, though, is realistic and knows results will ultimately dictate how the former Real Madrid and Inter manager fares back in English football.
"I have been in this situation eight times saying, ‘I think this is the manager who will stay’. And a year or two years later I was sitting here saying the same thing," Cech told The Daily Telegraph.
"This is how football goes and you never know. It all depends on circumstances, it all depends on the way the team will progress, the way results will go, and the ideas the board or the owners will have. You hope the manager will be there, renew the contract, stay forever."
Mourinho's glittering managerial CV includes Uefa Champions League successes with Inter and Porto and domestic league title wins in his native Portugal, England, Italy and Spain.
On what makes the 50-year-old so successful, Cech added: "I think it's the mentality, the wording and detail he puts in everything.
"He's one of the managers who would rather lose than draw.
"He's all about winning in the right way. That means you are tactically prepared and use the weapons to kill your opponent. I think Jose Mourinho will always make you see what he wants you to see.
"He understands people are different. No matter if you played one or 10 games under him, you really feel a part of the team.
"He is very demanding so everyone really is on top of your game whether you play or don’t play."