After losing his debut by 6-round decision to Joe DeFayette, Eklund won 10 straight fights; defeating such opponents as Doug Romano, Terry Rondeau, Carlos Garcia, Randy Milton, and Mike Michaud.

Before his 1978 match with future world boxing champion Sugar Ray Leonard, Eklund's most impressive victory was over undefeated Rufus Miller (6–0–1) in 1976.

Eklund's most notable fight was on July 18, 1978, against Sugar Ray Leonard at the Hynes Memorial Auditorium in Boston, Massachusetts.

On October 25, 1983, Eklund defeated James Lucas to win the USA New England Welterweight Title.

Paramount Pictures' 2010 drama The Fighter chronicles the rise of Eklund's younger half-brother Micky Ward.

Directed by David O. Russell, the film stars Christian Bale as Eklund and Mark Wahlberg as Ward.

In the documentary, Eklund was sentenced to a long prison term for crimes he committed to feed his crack addiction.