Lorenz began his career supporting singer Mariah Carey on her first promotional tour in 1990, and the following year he provided background vocals on her album Emotions. Lorenz again served as Carey's backing singer on her March 16, 1992 appearance on the television show MTV Unplugged, where he and Carey sang a cover of the Jackson 5's "I'll Be There" - a duet the two reprised at Michael Jackson's memorial at the Staples Center inLos Angeles, California on July 7, 2009. Their Unplugged performance was released as a single that went to number one in the United States. Lorenz also recorded a duet She Deserves It with Polish vocalist Basia on her gold U.S. album The Sweetest Illusion.
Lorenz was subsequently offered a record deal and recorded a critically successful self-titled debut album. The single "Someone to Hold" (co-written and co-produced by Carey, who also sang backup vocals) peaked at number nineteen on the U.S. Billboard Hot 100 singles chart. The album itself, however, performed poorly and only peaked at #111 on the Billboard 200 albums chart, and Lorenz was dropped by his label.
Lorenz returned to a career in background vocals, working for artists such as TLC, the late Selena, and Usher and also performed a duet with Basiatitled "She Deserves It" . He also appeared on Redhead Kingpin and the F.B.I.'s 1991 sophomore album The Album With No Name on the songs "It's A Love Thang (Word)", "Nice And Slow" and "Get It Together". He began to support Mariah Carey on her albums and concert tours again in 1997, including a featured spot in the 2003Charmbracelet World Tour, and he recorded the songs "Make You Happy" for the Men in Black soundtrack, which he co-wrote with Carey and Cory Rooney, and "I'm Still Not Over You" for theMoney Train soundtrack. He was signed to Carey's short-lived imprint label, MonarC, and to Jermaine Dupri's Atlanta-based So So Def Records label, but never put out any music under the label.
Lorenz's second album, Mr. Mista, was released on September 16, 2006. Among the songs on the new album is "See You Sometime", a song Lorenz sang during the Charmbracelet World Tour. Lorenz launched his second album during the time he was prominently featured in Carey's 2006 The Adventures of Mimi Tour, doing background vocals and singing three songs, "Never Too Much", "A House Is Not a Home" and "Crazy", during one of her many costume changes.
Trey Lorenz appeared on Jessica Simpson's 2010 PBS Christmas Special, singing a duet version "O Holy Night" with her.