Varsity baseball is the oldest Colby athletic team, having starting play in 1867. The Mules have won numerous Colby-Bates-Bowdoin (CBB) titles and Maine State titles and appeared in many ECAC tournaments over the long history of the program. The program also produced four All-Americans.

Jack Coombs '06 was the first Colby player to make the major leagues when he joined the Philadelphia Athletics in 1906. The field where Colby plays on campus is named after Coombs and was renovated in 2001.

John Winkin posted a 292-244-10 record during his 1954 to 1974 coaching career at Colby. He was the College Division National Coach of the Year in 1965.