The 2018 Seattle Sounders FC 2 season was the club's fourth year of existence, and their fourth season in the United Soccer League, the second tier of the American soccer pyramid.

Note: Flags indicate national team as defined under FIFA eligibility rules.

Source: USL Win Draw Loss Upcoming fixture Numbers after plus-sign(+) denote appearances as a substitute.

For transfers in, dates listed are when Sounders FC 2 officially signed the players to the roster.

For transfers out, dates listed are when Sounders FC 2 officially removed the players from its roster, not when they signed with another club.