League FC Tacoma 253 was announced as an
National Premier Soccer League expansion team in November 2014, with plans to begin play the following season. Tacoma tied
Real San Jose, 1-1, at home in its first-ever league match on March 28, 2015. Abdi Galgalo scored the team's first league goal. The club's first notable signing was of
Oussama Essabr, a Moroccan product of the
Juventus F.C. Youth Sector. Shortly thereafter, the club acquired Samuele Piccinotti from
Serie D A.S. Varese 1910's academy along with Marco Dugo, Gianmarco Peressini, and
Stefano Layeni. The team finished its inaugural season as champions of the Northwest Conference, which secured qualification for the
2015 NPSL West Region playoffs. However, the team lost to
Sacramento Gold FC, 3–2, in extra time in its first match. During the offseason, following meetings between head coach Filippo Milano and owner Giuseppe Pezzano, the team re-branded to
OSA FC with plans to integrate more Italian talent alongside young American players. The newly branded team finished the
2016 NPSL season first in the Northwest Conference for a second straight year, defeating
Portland Spartans FC, 2–1, on July 2. OSA earned the organizations first playoff win the
West Region first round when it beat
CD Aguiluchos USA, 3–2, on the road. The team fell to West Region top seed
Albion SC Pros in the region semifinal. Prior to the
2020 NPSL season, the team changed its name to
OSA Seattle FC.
U.S. Open Cup Prior to the 2015 regular season's start Tacoma played its inaugural match on February 20, 2015 in a
qualifier for the 2015 Lamar Hunt U.S. Open Cup, in which they defeated fellow Northwest Conference team and Oregon-based
Spartans Futbol Club, 2–1, at
Starfire Sports. On March 22, 2015, In its second match, FC Tacoma beat Southwest Conference representative
San Diego Flash, 6–1, at
Memorial Stadium (Seattle), and officially qualified for the
2015 U.S. Open Cup. Tacoma faced the
Kitsap Pumas in the first round of the tournament on May 13, 2015, and lost, 5–2. Steven Wright scored the team's first ever goal in the tournament, while Pedro Milan picked up the second. The team, now playing under the OSA name,
qualified for a second time via an at-large bid based on its
2016 NPSL results. In the
2017 U.S. Open Cup First round, OSA won its first ever tournament game when it defeated
Seattle Sounders FC U-23 in a penalty kick shootout, 0-0 (5-3), on May 10, 2017. A week later in the second round, the team played to a second straight penalty kick shootout against
United Soccer League side
Reno 1868 FC where it lost, 1-1 (3-4). ==Stadiums==