After being expelled from art school, Serious co-wrote, co-produced, edited and directed at age 21 his first film, Coaltown, "with the assistance of the Australian Film Institute". Released in 1977, Coaltown explores the social and political history of coal mining.

In 1988, Serious co-wrote, produced, and directed Young Einstein, an intentionally inaccurate movie portraying Albert Einstein as a young farmer in Tasmania who derives the formula E=mc² while trying to discover a means of creating beer bubbles, splitting the beer atom in the process. After leaving Tasmania for Sydney on the mainland to patent his discovery, he goes on to develop rock music and surfing, romances Marie Curie, and saves Paris from an atomic bomb. The film's popularity propelled Serious to stardom which saw him appear on the cover of Time and Mad magazines, and even get his own primetime slot on MTV. The movie was a success in Australia but a critical and commercial flop in the United States.

In 1993, Serious released his next film, Reckless Kelly, a satire about a modern descendant of the notorious Australian bank robber Ned Kelly who also becomes a movie star in Hollywood. While Reckless Kelly was a hit in Australia, it failed outside of the country and ended Serious's bid for mainstream international popularity. In 2000, Yahoo Serious released his third film, Mr. Accident, about the most accident-prone man in the world. Like Reckless Kelly, the film was not a commercial success.

He received an honorary doctorate from the University of Newcastle in 1996.

In August 2000, Yahoo Serious tried to sue the search engine Yahoo! for trademark infringement. The case was thrown out because Serious could not prove that he sells products or services under the name "Yahoo" and therefore could not prove that he suffered harm or confusion due to the search engine.

Shortly after the production of Young Einstein, Yahoo Serious married Lulu Pinkus. Their relationship ended in 2007.