[10][11] For his junior year in 2020, he pitched to a 1–1 record and a 3.60 ERA over four starts before the college baseball season was cut short due to the COVID-19 pandemic.
Eder was selected by the Miami Marlins in the fourth round of the 2020 Major League Baseball draft with the 104th overall pick and signed.
[14] In mid-August, he was placed on the injured list, and later that same month, it was announced that he would undergo Tommy John surgery, forcing him to miss the remainder of the 2021 season and all of 2022.
[20] After the season, Eder was selected to play in the Arizona Fall League for the Glendale Desert Dogs.
[22] On July 10, 2024, Eder was promoted to the major leagues for the first time to serve as the 27th man in the team's doubleheader against the Minnesota Twins.