Mourinho enjoyed a highly successful three years at the Stamford Bridge helm before making a shock exit in September 2007.
Widespread reports suggest Mourinho is in line for a return to west London to replace interim boss Rafa Benitez this summer.
Lampard was an integral member of the side that enjoyed so much success under the Portuguese and would welcome the 'Special One's' return.
"I think it would be a great thing for the club," said Lampard. "He is a successful manager and he would be a great thing for any club.
"It's hard to comment with the season still ongoing and with the manager not here or chosen yet. It would be easy to speculate.
"I have seen speculation before and a completely different manager walks through the door so you never know on that front.
"But he is certainly one of the greatest, if not the greatest, manager in world football."
Whether Lampard is here to welcome Mourinho back as a player or interested observer is not yet clear.
The 34-year-old's contract expires this summer and no new deal has yet been agreed, although reports suggest the former manager's return would see him offered an extension.
"I honestly don't know [whether Mourinho's return would help my cause]," added Lampard.
"We have got two weeks that will decide whether our season has been a successful one or not. That is the main focus.
"Of course Jose Mourinho would be a great manager for any club to have but I don't think it is right to talk about him while he is still Real Madrid manager."