The promising 22-year-old has spent a second season out on loan at Mick McCarthy's Wolves, where he helped the Midlands club remain in the Premier League during an impressive spell.
Mancienne proved to be a capable operator at the back or in a holding midfield role at Molineux, however the expiry of his deal means he is due to return to Stamford Bridge for pre-season training.
The England Under-21 international helped McCarthy's team reach the top flight two years ago and was able to return to the club following promotion.
And after gathering vital experience in the firing line, Mancienne fears it will be time to leave the club he supports - even though he doesn't want to.
Mancienne told the Daily Mirror: "I want to play for Chelsea, I want to be able to break into their first team but I know how much quality they've got in the side so it will be very difficult.
"But I'm 22 now, I've had two seasons out on loan at Wolves and had regular games and really enjoyed it. Now I want to be settled at one club so I know where my future is long-term and really try to push on.
"I'm a Chelsea fan, I've been at Chelsea since I was a kid, I've grown up at the club but it's hard for any young player to break into the team at a big club so I don't really know what's going to happen."
A move away from the London club may prove difficult for him, though, as he still has three years remaining on his contract with Carlo Ancelotti's side.
Mancienne received a shock call-up to Fabio Capello's senior England squad for a friendly against Germany last season and after representing the Three Lions at Under 16, 17, 19 and 21s level he is keen to break into the full international fold.
But the former QPR loanee knows that his ambitions will only be fulfilled by playing regularly - leading him to ponder his future during the close season.
He went on: "I've got three years left of my contract, I'm due to go back to Chelsea, start pre-season training again and take it from there.
"I'm at a stage of my career, though, where I need to be playing regularly because I've got big ambitions.
"I loved getting the call-up for England and of course I'd love to play for my country in the future and to do that I need to be playing games.
"If I go back to Chelsea for pre-season I'll be giving everything but I'd like to think it will either be with a chance of getting some games or maybe it's time to think about my future."