In 2012, Long and director Doug King produced two short comedy films in Glasgow called Let's Go Swimming and Romance and Adventure, which were nominated for a BAFTA Scotland New Talent Award.

Long was born in Sidcup and spent her early life in Orpington, London,[2] where she attended Newstead Wood School for Girls.

At 18 she gave up stand-up whilst attending Lady Margaret Hall, University of Oxford, ran experimental comedy clubs, and graduated with a degree in English.

[5] She contributed sketches and one-liners to BBC Radio 1's 2004/5 comedy show, The Milk Run[1] with Andrew O'Neill.

One edition of the show was entirely given over to a script she co-wrote with her friend Dan Harkin, entitled The Adventures Of Marco Polo.

[13] She has also been involved in BBC Switch, on a weekly mini-feature called Josie Long's Confuse the Teacher Feature, where a word is read out by Long for young people listening to the show to include in their homework, which was formed after her suggestion of the idea during an interview on the show with Annie Mac.

[citation needed] On 28 September 2008, she performed at the HungaMunga Festival at Bethnal Green Working Men’s Club.

[citation needed] On 18 March 2010 she appeared on the BBC Two comedy quiz TV programme show The Bubble.

[citation needed] Since 2010, Long has been involved with the anti-tax-avoidance activist group UK Uncut, and in 2011 co-founded The Arts Emergency Service,[16] a charity helping young people in education.

[19] Long and director Doug King also produced two short comedy films in Glasgow called Let's Go Swimming and Romance and Adventure, which were nominated for a BAFTA Scotland New Talent Award.

[20] Long has been a Doctor Who fan since she was a child[21] and she is interviewed for the special features of several classic series DVD releases, including Nightmare of Eden and Dragonfire.

[23] Drawing on this, Long's show at the 2019 Edinburgh Fringe, Tender, discussed the subject of childbirth and optimism about the future.

A review in Chortle noted that "[the] whole act is well refined with funny voice breaks,  emotional act-outs, exaggerations and unexpected callbacks.

"[24][25] Also in 2019 Long and Liam Williams wrote and starred in Perimeter, a dystopian play about a city divided into rich and poor areas by a giant fence.