As a senior, Cousins had a 7–2 win–loss record with a 3.15 earned run average (ERA) and was named unanimous first team All-Ivy League.

[4] He made his professional debut with the GCL Nationals in 2017, and also played with the Low-A Auburn Doubledays, accumulating a 2–2 record and 2.48 ERA in 18 appearances.

In 14 games between the AZL Brewers and Wisconsin, Cousins posted a cumulative 3–0 record and 1.91 ERA with 39 strikeouts in 28.1 innings of work.

On July 7, Cousins earned his first career win after pitching a scoreless inning in relief against the New York Mets.

He had turned down Tommy John surgery and received a platelet-rich plasma injection a few weeks earlier.

[16] He struggled to a 9.00 ERA in 8 appearances for the Triple–A Sugar Land Space Cowboys prior to being designated for assignment on August 29.

[20] On March 31, 2024, the White Sox traded Cousins to the New York Yankees in exchange for cash considerations.

[22] On August 13 against the Chicago White Sox, Cousins recorded his first career save in a 4-1 Yankees win.

[23] Cousins married his high school sweetheart Kelsey Ridderhoff on December 16, 2017, in Beach Park, Illinois.