The contract sees the business supply 289 Asda stores across England and Wales with its Bavarian fresh cream and fruit-flavoured tarts, available in mandarin, berry and strawberry.
In a statement, Asda said the deal was part of its long-term commitment to supporting local suppliers.
Currently selling over 107,000 tarts a week and supplying 56 Asda stores across Scotland, Mathiesons anticipates the new deal with see 2.9m tarts being produced per year.
Lorna Love, Mathiesons sales director, said this was an “exciting opportunity” for the business.
“It’s fantastic that Asda is continuing to support our brand, and we’re really excited about introducing our other flavours in due course,” she said.
Lisa Prudhoe, Asda’s customer planner for Scotland and Northern Ireland, added: “Mathiesons is the perfect example of how Asda are able to support and nurture the businesses of local Scottish producers. Their range of cakes and confectioneries are the perfect sweet treat and we’re confident our customers in England are going to love them.”
The bakery employs 200 people and produces a range of hand-crafted bakery and confectionery goods.