Born in Danvers, Massachusetts, Brad Delp's interest in music began at age thirteen, when he bought a guitar after seeing The Beatles perform on The Ed Sullivan Show. In 1970, he was making heating elements for Mr. Coffee machines at Danvers company Hot-Watt when he met Boston founder Tom Scholz, guitarist Barry Goudreau and drummer Jim Masdea.
Brad Delp auditioned as lead vocalist for Boston, and got the job immediately. He also contributed back-up vocals, guitar, and keyboards on the Boston albums, and also played the harmonica. His partnership with guitarist Tom Scholz led to a string of hit songs. In fact, On the first three Boston Albums, Brad Delp's voice is the only one that is used. He did all of the lead and backing vocals.
Following the 1978 album Don't Look Back, Brad Delp left to be lead vocalist for the Barry Goudreau band headed by former Boston lead guitarist Barry Goudreau. Brad Delp also contributed backing vocals to the band Orion the Hunter released in 1984, another band from Goudreau. He returned to the group Boston to record Third Stage, released in 1986.
On the 1994 album Walk On, Fran Cosmo replaced Brad Delp who was working with Return to Zero, but the album did not sell as well. Delp later shared vocals with Cosmo in concert, where Delp said Cosmo covered "the really tough high parts."
Brad Delp returned to the Boston line-up for the 2002 release, Corporate America, where he contributed lead vocals to several songs as well as backup vocals to others.
Later, Brad Delp played in a Beatles tribute band called Beatlejuice when he had time off from the band. Delp also performed with Goudreau on an album released in 2006, titled Delp and Goudreau.
After a first marriage to Kathy Stevens, whom he married in 1973 and divorced in 1978, he married Micki Delp and had two children with her, prior to their divorce. He had been a vegetarian for over thirty years and had contributed to a number of charitable causes. Brad Delp was set to marry longtime girlfriend Pamela Sullivan during a two day break in Boston's 2007 summer tour.
Brad Delp was found dead in his home in Atkinson, New Hampshire, on March 9, 2007. That day, the official Web site for the band was taken down and replaced with the statement: "We've just lost the nicest guy in rock and roll." Initial statements by his family, by Tom Scholz and by Barry Goudreau expressed similar sentiments. On March 14, Brad Delp's family revealed that his death was a charcoal-burning suicide and he was found by his girlfriend. Associated Press reported that, according to the New Hampshire medical examiner, Delp's death was the result of carbon monoxide poisoning. According to police reports released on March 15, Delp was found dead in his bathroom with a note that read: "Mr. Brad Delp. J'ai une ame solitaire. I am a lonely soul."
In response to suggestions that pressures from within the band contributed to Brad Delp's untimely demise Boston band leader Tom Scholz and fiancee Pamela Sullivan have made statement's to the contrary.