In addition to his science and maths books, which include books on Isaac Newton (Dead Famous: Isaac Newton and his Apple), and various galaxy puzzles, practical jokes and secret codes, Poskitt has written a book of magical tricks, a GCSE Maths support book and four Rosie and Jim annuals. In 2007, Poskitt published the first in a series of children's novels called Urgum the Axeman. Since then he has written the "Borgon the Axeboy" series and the award winning "Agatha Parrot" series.
He also wrote the theme tune for the children's art program SMart, as well as the title theme and music for the first two series of Brum. He is also the creator of a logic puzzle, Kjarposko.
He has been a presenter for a number of (mostly BBC) educational children's TV shows.