Born in Knowsley, Merseyside in 1997 and raised in nearby Grappenhall in Warrington, Cheshire. He studied at Broomfields Junior School and Bridgewater High School.

Roskell had his first acting role in the ITV miniseries Mobile in 2007; the following year, he was part of the main cast of TV series The Revenge Files of Alistair Fury, broadcast by BBC One and the CBBC Channel; he played the role of Aaron Pryce, a friend of main character Alistair Fury (played by Jonathan Mason). In 2010, Roskell branched out into theatre following a successful audition for the musical Her Benny, adapted from the eponymous Victorian novel (1879) about Liverpool street children by Silas Hocking. Roskell played Perks, one of the street children, over the show's October run at the Theatre Royal in St Helens.

From 2011 to 2014, Roskell portrayed Sean Spencer in the long-running soap opera Emmerdale, appearing in a total of 264 episodes. After leaving the show, he returned to the stage in 2015 to take on the role of Carl Jackson, the lead in Gareth Farr's play Britannia Waves The Rules, touring with the Royal Exchange Theatre through several locations in North West England.

In 2016, he portrayed Dan in the autism TV drama The A Word in three episodes of its first series. He was later cast in the historical drama Jamestown as Pepper Sharrow, the youngest of three brothers living as first settlers of the Colony of Jamestown in the early 17th century.