Her big break came as Jess Brown in the American sci-fi series Tracker, appearing in 8 episodes between 2001-2. She appeared in 20 episodes of the BBC day-time medical drama series Doctors in 2001, but her best known role is that of Claire Guildford in 90 episodes of the BBC One medical drama Casualty. She appeared in the BBC's Stars in Fast Cars' as herself' in 2005, presented an award at the Disney Awards and made a couple of appearances on GMTV. After leaving Casualty she guest starred in Channel 4's comedy series Peep Show in 2007. She has also appeared in numerous commercials and is currently pursuing her acting career in Los Angeles.

She appeared in the films Is Harry on the Boat? in 2000, and The Holiday in 2006. Leanne married her partner Keith Whallett in 2006.

Leanne was voted into 70th place in FHM's 100 Sexiest Women in the World in 2005.

On 9 August 2009, it was announced that Leanne Wilson is due to appear in a comedic t.v. series called 'Workshop'. She has also shot a pilot for a new sit-com called 'T.V or Not T.V' is shooting an episode of 'The Anthony Falcon Show' and has just starred in NBC/FOX 'Better Off Ted'.