Defence Secretary Des Browne has announced that the future of Devonport Naval Base is secure.
Nuclear missile submarines are refitted at Devonport
There had been fears that it could close as part of the Ministry of Defence's (MoD's) naval review.
Devonport in Plymouth has missed out on building two new aircraft carriers, the largest ships ever commissioned by the Royal Navy.
But Mr Browne told the Commons that it will remain open, although some cuts may be necessary.
Devonport currently employs about 2,500 civilian and service personnel and is home to 25 major ships.
Its future was considered in the review alongside Portsmouth, where the carriers will be based, and Faslane.
Mr Browne also announced that the navy would retain all three bases, although with the loss of some jobs among the 17,800 employees across the three sites.
South West Devon MP Gary Streeter (SW Devon) asked for assurances that Devonport would not be "condemned to death by a thousands cuts".
Mr Browne said there was no intention to do this.
Refusing to "bandy around" figures for job losses, he said: "I am advised that we can sustain significant bases in all three places."
The two carriers will be built by an alliance including Devonport's new owner, Babcock, and assembled at the Rosyth Naval Base in Fife .
Commodore Simon Lister, Devonport Naval Base Commander, said: "I see this is an opportunity for specialists wherever they work in Babcock.
"They are as likely as anyone in Babcock to be drawn in to the construction of the carrier."