Botnick engineered Love's first two albums, and co-produced their third album, Forever Changes, with the band's singer-songwriter, Arthur Lee. He also is listed as the one of two recording engineers on the LP by Curtis Amy, The Sounds of Broadway - The Sounds of Hollywood, which is said to have been released in 1965, although it also has been said to have been released earlier. The LP back cover (liner notes) are written by Curtis Amy, where he formally thanks Bruce Botnick for his work on the recordings.
Botnick audio engineered the Doors' studio recordings starting with their first album in 1966.
In November 1970 he took over production of The Doors' L.A. Woman album, their last with lead singer Jim Morrison, after the band's long-serving producer Paul A. Rothchild fell out with the band over the album's direction. According to Robby Krieger it was Botnick's idea to record the album at the Doors rehearsal space where they were more comfortable and used to the sound, rather than at a more costly recording studio.
Botnick has a credit as assistant engineer on the Rolling Stones' Let It Bleed album. He later produced Eddie Money's first two albums, Eddie Money in 1977 and Life for the Taking in 1978. Botnick also produced two albums for Paul Collins' rock group The Beat, including 1979's The Beat and 1982's The Kids Are The Same. He also co-produced Kenny Loggins’ 1982 album, High Adventure.
Botnick had a long-running association with film composer Jerry Goldsmith as his scoring mixer. Botnick first met Goldsmith on 1979's Star Trek: The Motion Picture and they worked together on most of Goldsmith's film projects - numbering over 100 - from the 1980s through to Goldsmith's death in 2004.
He also engineered at least two of Lonnie Mack's late-60s Elektra albums.