College and amateur Marcinkowski played for the
Georgetown Hoyas for three seasons, from 2015 to 2017, where he achieved a 0.84 goals against average (GAA) over 56 appearances. In his final season at Georgetown, he captained the team to a
2017 Big East Conference Men's Soccer Tournament championship win, his second with the team. He also played two games for the
USL PDL side
Burlingame Dragons.
Professional Marcinkowski signed a
Homegrown Player contract with the
MLS side
San Jose Earthquakes on December 6, 2017, after spending four years prior to his college career with the team's academy. He was San Jose's third ever Homegrown signing to the first team, after
Tommy Thompson and
Nick Lima. Marcinkowski was then temporarily loaned to San Jose's
USL affiliate
Reno 1868 FC, and played his first game for the team in Reno's 3–4 loss to
Swope Park Rangers on March 17, 2018. On January 16, 2025, Marcinkowski signed a two-year deal with
LA Galaxy as a free agent.
International Born in the United States, Marcinkowski is of Polish descent. He has played for the
United States' men's national team at multiple levels, earning 24 caps between the U14 and U18 levels. In 2017, he played for the U20 squad, at the
2017 CONCACAF U-20 Championship and the
2017 FIFA U-20 World Cup. Marcinkowski was named to the final 20-player
United States under-23 roster for the
2020 CONCACAF Men's Olympic Qualifying Championship in March 2021. ==Career statistics==