In 1988, Martin teamed up with Billy Sheehan, Pat Torpey, and Paul Gilbert to form Los Angeles supergroup Mr. Big. The band combined "shredding" musicianship with melodic vocal harmonies.[7] The reputations of the players generated immediate interest in fellow musicians, and the band was signed to Atlantic Records in 1989. That year, the band released their eponymous debut, which received critical and commercial success in the US and Japan. In June 1990, the group toured America with the Canadian band Rush.
The group's 1991 release, Lean into It, featured two ballads that established them as a commercial success: "To Be with You" (number one song in 15 countries) and "Just Take My Heart".[10] The album was followed by a British tour in April and May of the same year, supported by bands The Throbs and Heartland.
In 2013, Martin was invited to be part of the metal opera project Avantasia, by Tobias Sammet. Martin played the role of a beggar on the album The Mystery of Time, performing What's Left of Me, with Sammet. Martin was also part of their 2013 world tour in support of the album as one of the guest vocalists. He is also part of their 2016 world tour in support of the album Ghostlights, notably performing the guest vocal role in the songs "Dying for an Angel", "The Wicked Symphony" and "Twisted Mind".[16]
In October 2014, Mr. Big released "The Stories We Could Tell," with 13 new songs and a bonus live track of "Addicted to That Rush." They embarked on a world tour to support the record and an unofficial fifth member of the band joined them on the tour: drummer Matt Starr. Starr (most notably from Ace Frehley's band,) is a talented drummer and singer, and Mr. Big recruited him to sit in for Pat Torpey, who had recently been diagnosed with Parkinson's disease. While Torpey did tour with the band, he played drums on only a few songs, and typically sat on a stool and sang with the band while Starr handled the rest of the drum duties. Additional dates are planned for rock cruises and West coast dates in early 2016.