The signing of Alphonse Areola means an end for Darren Randolph who is now considered surplus to requirements by the club.
They will try to find him another club before the end of the summer transfer window at the end of August but admit it may be hard to place him in time.
The Hammers paid £4m to Middlesborough last year for cover for Fabianski and flop keeper Roberto.
He signed a three-year contract with the Hammers contracted him until June 2023 but he is likely to move on before completing his second contract with the Hammers.
He is not on huge wages in Premier League terms so could be attractive to Championship clubs pushing for promotion.
Both Randolph and Fabianski have become more injury-prone in recent seasons meaning it is likely to be all change in the first team goalkeeping department.
Fabianski is likely to play understudy to Areola with just twelve months remaining on his extended contract.