Born in Shelton, Connecticut, Trey McLoughlin attended the eponymously named high school in his hometown. Ater graduating, he attended Fairfield University about a half-hour down I-95. In his freshman season, the right-hander posted a 5.60 ERA in 45.0 innings, allowing 53 hits, walking 22, and striking out 22. He supplemented his time on the mound after the season ended by playing with the Danbury Westerners of the New England Collegiate League that summer, and then returned to Fairfield in 2019 for his sophomore season. He showed only marginal improvements in some areas but showed great growth in others, posting a 5.