He has also appeared in a third soap opera, EastEnders, as the hitman Carter who supposedly killed Paul Trueman under the orders of Andy Hunter.
He came to prominence in the mid-1990s as the character Tony in a series of British television commercials for the Peugeot 106 car, alongside Julie Graham and Annie Dunkley.
He appeared in an episode of BBC afternoon drama-comedy Shakespeare & Hathaway: Private Investigators entitled "The Rascal Cook", in which he played Len Tekler.
McKell starred in the cult film Essex Boys alongside Sean Bean as drug dealer Wayne Lovell.
Other films include Beneath Still Waters, Acts of Godfrey, The Low Down, Blood, Bar, Death, Freight, Shouting Men, Outpost: Rise of the Spetsnaz, Hatton Garden: the Heist, and Who Needs Enemies.
Recently, McKell played the titular roles in Steve Lawson's 2021 film Jekyll and Hyde, and appeared in 2022's Prizefighter with Matt Hookings, Ray Winstone and Russell Crowe.
From January to July 2015, McKell co-starred with Tina Hobley, Jamie Lomas, Rik Makarem and Gray O'Brien in a nationwide touring production of Peter James's Dead Simple.