Leach began his stand up career in February 2010, performing on the UK comedy circuit and at the Edinburgh Fringe Festival. He was a finalist in the London New Comedian Award 2010, Laughing Horse New Act 2011 and a semi-finalist in the Leicester Square New Comedian 2011. He performed at the Edinburgh Fringe Festival in 2011 and 2012 with promoters Live Nation becoming a Top Ten Finalist in the Amused Moose Laugh Off Competition 2012. During that same year he signed a development deal with BBC Worldwide Consumer Products’ Division owned DVD and distribution company 2Entertain.
In May 2014 Leach embarked on his debut solo comedy tour entitled ‘Jeff Leach. FIT’, performing across the UK, Guernsey, Romania, Serbia, Croatia and New York in various theatres with critical acclaim.
His first professional theatre work was with the Royal Shakespeare Company during the Complete Works of Shakespeare Festival season playing the lead in Lope de Vega’s ‘The Capulets and the Montagues’. In 2013 Jeff completed a role in short film Shop Girl Blog and played rocker Lenny in online comedy series The Chaos which amassed over 7 million views. During 2014 he played the role of Simon in Channel 4 show Hollyoaks and also He also played the role of Dean in feature length independent British gangster thriller film The Smoke directed by Ben Pickering which was released at the end of 2014.
During 2015 he appeared in a number of short films including playing the main role in Gerry’s Garden which was selected to be shown during the prestigious London Short Film Festival, won a comedy award on the industry website Shooting People and at the Berlin Short Film Festival as well as being selected by Future Shorts to showcase on their YouTube channel.
In July 2015 it was confirmed that Jeff Leach would play Ronnie in Derrick Borte‘s London Town  featuring actors Jonathan Rhys Meyers, Dougray Scott and Daniel Huttlestone. It got released in 2016.
During his early career in radio Leach provided voice work for BBC Radio 1‘s Scott Mills Drive-time, Xfm‘s Lauren Laverne show and Tim Shaw’s Asylum on Kerrang! Radio. He was also a station producer for GCAP Media station Mercia FM whilst at university. For two years he hosted a comedy podcast for Total Rock Radio and currently hosts his own weekly comedy show on Soho Radio.