Born in Danbury, Connecticut, Brandis got his show-biz break at the age of six when he landed a recurring role on One Life to Live and appeared in numerous commercials. He moved to Los Angeles with his family at age nine and made guest appearances on shows such as L.A. Law, Who's the Boss?, Murder, She Wrote and Kate & Allie.

He received his first starring role in The NeverEnding Story II, and went on to appear primarily in television roles. Of these, he is most famous for his portrayal of scientific prodigy Lucas Wolenczak in Steven Spielberg's futuristic science fiction series seaQuest DSV. He is also well known for voicing Mozenrath in Disney's television series Aladdin, and having played Barry Grabrewski in the film Sidekicks co-starring Chuck Norris. He also starred in the soccer movie Ladybugs with actor/comedian Rodney Dangerfield.

During his lifetime he was romantically linked to Tatyana Ali, Heather McComb, Vinessa Shaw and Monica Keena. He accompanied actress Brittany Murphy to her high school prom.

He expressed an interest in moving his career towards more directing work rather than acting. He had also auditioned for the role of Anakin Skywalker in George Lucas' Star Wars Episode II: Attack of the Clones.

On November 12, 2003, Brandis died from injuries he suffered after hanging himself the previous day. According to his mother, he went out to dinner with friends, then they went back to his apartment at 650 S. Detroit St. His friends reported that he seemed to be agitated and pacing around quite a bit. He left the room and, approximately 15 minutes later, one of his friends went looking for him and found him hanging by a nylon rope in the second floor hallway of his building. His friends cut him down and called paramedics. Despite all efforts to revive him, he was later pronounced dead.

Brandis apparently did not leave a note of any kind. His family was devastated upon receiving news of his death. He had no known personal problems, except for the fact that he was usually quite hard on himself. According to his mother, he had no prior suicide attempts, drank socially and had quit smoking two years prior, along with recreational drugs. Brandis's mother questioned whether his use of the acne drug Accutane may be to blame, citing that one of the clinical side effects was reported to cause psychosis and suicide. In a People magazine article, friends were quoted as saying he was lonely and depressed about his lagging career. One friend admitted that Brandis drank heavily, and had even mentioned that he might kill himself. He was also said to be upset when his appearance in Hart's War, a role he hoped would be his comeback, was cut from the film.