The actor, best known for his role as stylist Gavin Ferraday on the BBC drama, has signed up to play a handsome business tycoon named Declan who becomes entangled in the life of murderess Natasha Wylde (Amanda Donohoe).
Declan will first appear on screen in April and be seen acquiring a stake of the village's Home Farm estate after a cash-strapped Natasha searches for investors.
The newcomer's involvement with Natasha will take a further twist, however, as viewers are left to wonder whether the newly-single businesswoman is looking for more than just a financial saviour.
Speaking of his new role, Merrells commented: "I'm thrilled to be joining a show as respected and well-loved as Emmerdale and look forward to filming my first scenes later this month. Declan's an enigmatic mogul who is bound to raise a few eyebrows in the village."
Emmerdale's series producer Gavin Blyth added: "I'm delighted to be welcoming Jason to the cast. He is an extremely talented actor and will be brilliant in the role of Declan. Jason's role will continue to take the show forward in this very exciting time for Emmerdale."
As well as Cutting It, Merrells has appeared in Casualty, Waterloo Road and Lark Rise To Candleford. He has also enjoyed a successful theatre career with the Royal Shakespeare Company.
The latest Emmerdale signing follows last month's announcement that former Hear'Say star Suzanne Shaw is to play Edna Birch's (Shirley Stelfox) granddaughter Eve on the programme.
Merrells's ex-Cutting It co-star Siân Reeves is currently appearing in the Yorkshire-based soap as Ashley Thomas's deranged suitor Sally Spode.