Mone, 26, is now under contract through 2024 and can make up to $13.8 million with incentives over the next three seasons, according to the source.
The extension, first reported by NFL Network, includes a $1.5 million signing bonus. He was already under contract for 2022 for the minimum salary of $965,000 after Seattle tendered him as an exclusive-rights free agent earlier this offseason.
Mone has gone from an undrafted free agent in 2019 out of Michigan to a key member of the Seahawks' defensive line. He started five of 14 games last season and recorded career highs in tackles (35) and sacks (1.5).
He joins Poona Ford as UDFA defensive tackles who have signed multiyear deals with the Seahawks since the start of last offseason. Ford, undrafted in 2018, signed a two-year deal last March.