The 1980 Eastern League season began on approximately April 1 and the regular season ended on approximately September 1.
The Holyoke Millers defeated the Waterbury Reds two games to one to win the Eastern League Championship Series.
Notes:
Holyoke Millers defeated Buffalo Bisons 2 games to 0.
Waterbury Reds defeated Reading Phillies 2 games to 0.
Holyoke Millers defeated Waterbury Reds 2 games to 1.