The actress, best known for her part as Val Pollard on the ITV1 soap, will appear as Sandy in the touring production from late February.
The Awkward Squad is billed as a "state-of-the-nation" play which takes a humorous look at the unexpected challenges faced by women of all ages. Emmerdale's BAFTA-winning writer Karin Young has penned the play.
Hardwick will take a 12-week break from Emmerdale for the new project, Digital Spy can confirm.
The Awkward Squad tells the story of a woman named Lorna, who is looking forward to receiving an honorary PhD. However, she soon has difficulties to deal with when her daughters and granddaughter descend on her with a series of problems.
The play's synopsis reads: "A BAFTA, impending divorce, redundancy and a very upmarket caravanette force Lorna to reconsider both the past and the future - for everyone. What's a woman to do? Accept everything that's thrown at her, or become a fully paid-up member of the 'awkward squad'?"
Ex-Casualty star Barbara Marten and former The Bill actress Libby Davison also star in the show.
The Awkward Squad will open at The Customs House South Shields on February 28. It will then be performed at London's Arts Theatre from March 6 and York Theatre Royal from April 9.
> Read more Emmerdale news and spoilers