On December 21, 2018, it was announced that Freese would leave Harvard early and join Major League Soccer club Philadelphia Union at the beginning of their 2019 season.[3]
Freese made his professional debut on April 19, 2019, coming on as a 54th-minute substitute for Andre Blake in a 3–0 home win against the Montreal Impact.
On November 8, 2020, Freese made his lone start of the 2020 season against the New England Revolution on MLS Decision Day. He made one save and kept a clean sheet as the Union clinched their first trophy in club history, the Supporters' Shield.[4]
New York City FC
On January 27, 2023, Freese was traded to New York City FC in exchange for a guaranteed $350,000 of General Allocation Money, with a possibility of an additional $400,000, as well as a percentage of a future transfer fee.[5]