Melenhorst has been director of animation at Iloura Post Production in Melbourne. He is the son of Dutch immigrant parents and was educated in Melbourne. He developed a strong interest in art, English and music. Melenhorst spent year 12 at Dandenong TAFE and then did a Diploma of Graphic Design at Swinburne Institute of Technology (now Swinburne University) followed by a further year acquiring a Diploma in Film and Television (Animation). He decided on a career in animation.

Glenn received a CBCA Crichton Award for New Illustrators for his children's book Little Boys. In 2011, he released a book app to accompany Little Boys, titled Food Fight.