He is best known for his work as showrunner, writer and executive producer of the drug and gang-related crime drama television series Top Boy.

Inspired by witnessing a twelve-year-old boy dealing drugs at his local Tesco supermarket in Hackney, Bennett created and wrote Top Boy, a British crime drama television series focusing on gang culture and drug dealing in a predominantly black council estate in East London.

He attended St Mary's Christian Brothers' Grammar School, Belfast, on the Lower Falls Road, where he became politically active.

[6] Bennett had been writing in prison to Iris Mills in Huddersfield,[7][8] to which he moved after his release from Long Kesh,[7] becoming involved with anarchist paper Black Flag.

[14] Anarcho-punk band the Poison Girls recorded a song "Persons Unknown" and released it as a joint single with Crass to raise money for Bennett's anarchistic Wapping Autonomy Centre.

[15] Mills and Bennett found funding, then rebuilt and decorated the centre, which did not last long, succumbing to vandalism by the punk fans it attracted.

[4][a] That same year, he was hired as a researcher by Jeremy Corbyn MP, later Leader of the Labour Party, in a move that provoked controversy and security concerns.

It has been supposed that Nigel Short's column was axed to make way for the new feature and the justification for this change has been the subject of some debate in chess circles.

"[28] In the same month, along with 42 other leading cultural figures, Bennett signed a letter endorsing the Labour Party under Corbyn's leadership in the 2019 general election.

The letter stated that "Labour's election manifesto under Jeremy Corbyn's leadership offers a transformative plan that prioritises the needs of people and the planet over private profit and the vested interests of a few.