He is known for his roles as Jambo Bolton in Hollyoaks, Gaz Wilkinson in Two Pints of Lager and a Packet of Crisps, Warren Stamp in EastEnders, DC Spike Tanner in No Offence, Steve Connolly in Broadchurch, Georgie in Barking!

He played Jack Vincent in Casualty from 2001 to 2003, and starred as Gaz Wilkinson in the comedy Two Pints of Lager and a Packet of Crisps from 2001 to 2011.

[3] Mellor starred as "Barmpot" in the postal worker drama Sorted, and played DC Jed Griffiths in the second series of Murder Investigation Team.

Mellor was a guest star in the BBC fantasy drama Merlin, playing the villain Valiant in the series second episode of the same name.

In February 2021, it was announced that Mellor would join the cast of Coronation Street as Harvey Gaskell, with his first scenes airing in March.

[12][13] From 24 September 2022, Mellor competed in the twentieth series of Strictly Come Dancing, partnered with professional dancer Nancy Xu.

In 2020, in a podcast with fellow actor and friend Ralf Little, Mellor discussed his struggle with depression after the death of his sister six years before.