The 42-year-old – who played Zoe Tate in the Yorkshire soap for 16 years – is due to begin filming with the Birmingham-based soap from Monday, June 25 for an episode entitled 'Brotherly Love'.
Leah takes on the role of Jennifer Bryant, a still-grieving widow who can't understand how she has contracted an STD when she lost her loving husband three months ago.
Producer Jonathan Phillips told DS: "We're all very excited about having Leah film with us. She's a fantastic and popular actress, and it's a real tribute to Doctors that we can attract such great acting talent."
Her episode will transmit on Thursday, October 11 on BBC One.
Leah also recently signed for new ITV Daytime drama The Royal Today.