Beginning his career as a child model, Brandis moved on to acting in commercials and subsequently won television and film roles.

In 1990, he portrayed Bill Denbrough in the television miniseries It, and starred as Bastian Bux in The NeverEnding Story II: The Next Chapter.

In 1993, at the age of 17, he was cast in the role of teen prodigy Lucas Wolenczak on the NBC series seaQuest DSV.

He moved to Los Angeles with his family at age nine and made guest appearances on shows such as Blossom; L.A. Law; Who's the Boss?

[4] At age 13, Brandis was cast in his first starring role as Bastian Bux in The NeverEnding Story II: The Next Chapter.

He played the young "Stuttering Bill" Denbrough in the 1990 television miniseries Stephen King's It, based on the epic horror novel of the same name.

Brandis was cast as the lead in two films made close together, first as Barry Gabrewski in Sidekicks and then starring as Matthew/Martha in Ladybugs.

Around age 17, Brandis landed one of his best-known roles, as scientific prodigy Lucas Wolenczak in Steven Spielberg's futuristic science fiction series seaQuest DSV.