Campbell began his musical journey as a teenage guitarist in Arkansas before relocating to California in 1960 to pursue professional opportunities. Initially performing with The Champs and recording unsuccessful pop singles, he became an in-demand session musician and a core member of the Wrecking Crew ensemble in Los Angeles. He contributed guitar work and backup vocals to recordings by major artists spanning multiple genres, including Merle Haggard, Frank Sinatra, and the Beach Boys, on whose landmark Pet Sounds album he performed and briefly replaced band member Brian Wilson during touring.

Campbell's solo career launched in 1966 and accelerated dramatically through the late 1960s and 1970s, generating a series of crossover hits that dominated both country and pop charts. Songs such as "By the Time I Get to Phoenix," "Wichita Lineman," "Rhinestone Cowboy," and "Southern Nights" earned him multiple Grammy Awards and established him as one of the era's most commercially successful recording artists. He remained a recording and performing presence for decades, releasing his final album in June 2017, just two months before his death from Alzheimer's complications in Nashville.