The group will join Polpo, Sticks'n'Sushi and Cinnamon Kitchen at the £440m Westgate Oxford scheme on 24 October.
Diners will sit around a central grill, which will serve Tommi's classic steak, chicken and vegetarian burgers garnished with iceberg lettuce, tomatoes and chopped onions. The restaurant will also be the only burger site in the food court to serve draught beer.
The first Tommi’s Burger Joint opened in Reykjavik in 2004 and was followed by a London pop-up in 2012.
The group now runs three permanent London sites in Marylebone, Chelsea and Soho, alongside six in Iceland, one in Berlin and one in Copenhagen.
“Oxford is a quintessential English city steeped in history and heritage,” says a representative for Tommi’s.
“We thought that it would be the ideal location for the next Tommi’s Burger Joint with its bustling city centre and strong student presence.”
Tomasson started out in the burger business in 1981, opening five Tomma-Burger restaurants in Iceland, before selling-up in 1983. He helped launch the Hard Rock Cafe in Reykjavik in 1987, which he ran alongside the city’s Hotel Borg for ten years.