Within a year, Steuer had received a minor guest-starring role on the television series Day by Day. In 1990, Steuer was cast as Alexander Rozhenko in the Star Trek: The Next Generation episode "Reunion". Although a number of young children auditioned for the role, Steuer was the only child able to sit still for the three hours it took for the make-up department to cast his Klingon facial prosthetics. The ability to be still for a long period of time won him the part. The producers of the series sought him out a year later to reprise the role. However, Steuer had only grown half an inch in height and, at six years old, did not have a deep enough voice. So the producers cast actor Brian Bonsall, who was more than two years older, as Alexander. Steuer later said he was very upset at being recast.
Steuer performed several more times over the next three years, including the 1991 comedy Late for Dinner, a guest shot in the episode "Unpacking" of the TV series The Wonder Years, and a role in the made-for-television movie When Love Kills: The Seduction of John Hearn (1993). In the fall of 1993, Steuer won the role of Quentin Kelly in the television series Grace Under Fire. But the extensive press attention given to lead Actress Brett Butler (due to her erratic behavior and substance abuse) led Steuer to quit the show. Although he auditioned for TV and movie roles after leaving Grace Under Fire, producers and press kept asking him about Butler and what it was like to work with her. Unwilling to continue to submit to such intense scrutiny, Steuer quit acting. He told an interviewer for The A.V. Club in 2015: "I wanted to forge on with acting after quitting the show, and I went out on a few interviews. But even then they'd turn into question-and-answer sessions with casting agents about Grace Under Fire. I was kind of blown away by how unprofessional people inside the industry were. It really soured me. I didn't want that kind of attention."
During his time on Grace Under Fire, Steuer was cast in the 1994 comedy film Little Giants. He co-starred alongside 13-year-old Sam Horrigan. Horrigan replaced Steuer in the role of Quentin Kelly after Steuer left Grace Under Fire.
Steuer eventually moved to Denver, Colorado. In 2003, he and several other local Musicians formed the glam punk band Kill City Thrillers. Steuer performed as lead singer for the band under the name Jonny P. Jewels. Within a few months, the band changed its name to Soda Pop Kids, and about 2005 the band and most of its members moved to Portland, Oregon. The band dissolved in November 2009.
In March 2015, after several years working as a bartender and server, Steuer partnered with chef Sean Sigmon to open Harvest at the Bindery, a vegan restaurant located in Portland.
Steuer died on January 1, 2018, aged 33. Upon Steuer's death, the restaurant closed permanently.
