Marlowe signed with the Mariners and made his professional debut with the Everett AquaSox of the Low–ANorthwest League with whom he batted .301 with three home runs, thirty RBIs, and ten stolen bases over 62 games.[6] He did not play in a game in 2020 due to the cancellation of the minor league season because of the COVID-19 pandemic.[7] He began the 2021 season with the Modesto Nuts of the Low-A West before he was promoted to Everett (now members of the High-A West) where he earned Player of the Month honors for July.[8][9][10] He also played in one game for the Tacoma Rainers of the Triple-A West at the end of the season. Over 106 games between the three teams, he slashed .275/.368/.566 with 26 home runs, 107 RBIs, 25 doubles and 25 stolen bases.[11] He was named the Most Valuable Player of the High-A West.[12] The Mariners also named him their Ken Griffey Jr. Minor League Hitter of the Year.[13] He was assigned to the Arkansas Travelers of the Double-ATexas League to begin the 2022 season.[14] He was promoted to Tacoma at the season's end.[15] Over 133 games between the two teams, he slashed .287/.377/.487 with 23 home runs, 102 RBIs, and 42 stolen bases.[16]
On November 15, 2022, the Mariners selected Marlowe's contract and added him to the 40-man roster to protect him from the Rule 5 draft.[17] Marlowe was optioned to Tacoma to begin the 2023 season.[18] In 69 games for Tacoma, he batted .255/.332/.461 with 11 home runs, 47 RBI, and 25 stolen bases. On July 20, 2023, Marlowe was promoted to the major leagues for the first time following an injury to Jarred Kelenic.[19] He made his MLB debut that night as the starting left fielder against the Minnesota Twins; in the game, he went 0–for–3 with a walk.[20]
On August 3, Marlowe hit his second MLB home run, a 405-foot go-ahead grand slam in the top of the ninth inning against Los Angeles Angels closer Carlos Estevez, giving the Mariners a 5–3 win. He became the first Mariners player to hit a go-ahead grand slam while trailing in the ninth inning or later since Richie Sexson on September 19, 2005, against the Blue Jays.[21] In 34 games during his rookie campaign, he batted .239/.330/.421 with three home runs, 11 RBI, and four stolen bases.
Marlowe was optioned to Triple–A Tacoma to begin the 2024 season.[22]
