The 23-year-old joins the Tangerines after leaving South African Premiership side Free State Stars in June.
"I'm very happy and feeling good. It's my first time in England and I'm happy to sign for Blackpool," said Mafoumbi.
The deal to sign Mafoumbi, who has 12 caps for Congo, remains subject to international clearance.
Mafoumbi is the second goalkeeper the club have signed in two days, after Ryan Allsop joined on loan from Bournemouth.
Find all the latest football transfers on our dedicated page.
Blackpool have signed Congo international goalkeeper Christoffer Mafoumbi on a two-year deal with the option of a further 12 months.