He wrote the Buster Bayliss series of books for young readers, which includes Night of the Living Veg, The Big Freeze, Day of the Hamster, and Custardfinger.

[5] The books feature two young adventurers, Tom Natsworthy and Hester Shaw, living in a lawless post-apocalyptic world inhabited by moving cities.

Reeve and Arthur won the annual Carnegie Medal from the British librarians, recognizing the year's best children's book published in the UK.

[12] Reeve began a series of Mortal Engines prequels with Fever Crumb (Scholastic UK, 2009).

[13] In March 2020 Reeve said he did not intend to finish or publish a fourth book in the Fever Crumb series, as too much time had passed, thereby forgoing the world of Mortal Engines.

[14] In 2013, Reeve had his first co-authored, highly illustrated book with British-American writer-illustrator Sarah McIntyre published by Oxford University Press: Oliver and the Seawigs.

[17] In 2018, Reeve praised the 2018 Mortal Engines film adaptation, saying the director, Christian Rivers, had "done a fantastic job – a huge, visually awesome action movie with perfect pace and a genuine emotional core....

This leads to thousands of words of rough draft material being abandoned – even entire novels, such as with Fever Crumb and Mortal Engines.

It usually takes him a year to move a novel from first idea to publication – six months actively writing it, the rest editing and thinking.