Blackwood played Lenny Henry's sidekick Winston Churchill in The Lenny Henry Show (1987) and David Sinclair in Casualty (1996–97). Since playing Rory Breaker in the hit film Lock, Stock and Two Smoking Barrels (1998) he has had a number of film roles, including Mean Machine (2001), 9 Dead Gay Guys (2002) and Creep (2004). In 2005 he appeared in A Bear's Tail, a spin-off of Bo' Selecta!. He also made an appearance as Lennox Gilbey in Only Fools and Horses. He also played main character Dexter in Spatz.
In 2008 he did voiceover work on the video game Fable II.
In 2013 he did voiceover work on a Tesco advertisement, this was launched and played on various different channels within the United Kingdom in the Summer period.
