The newly-created chief marketing role will cover sales, brand marketing, new product development and innovation. Somers will report to Domino's chief executive David Wild directly.
Last year, Somers left McDonald's after three years to set up her own marketing and communications consultancy.
While at McDonald's, she became the group’s most senior marketer in the UK following the promotion of Alistair Macrow, formerly chief marketing officer, to a global role earlier this year.
She also launched a campaign to mark the 50-year anniversary of the Big Mac, as well as an advertising push that sought to debunk the rumours of what McDonald’s puts in its products.
Before McDonald's, Somers served in a variety of industry roles including the managing director of Havas London and client services lead at Leo Burnett. She was also a consultant for the BBC.
On her decision to join Domino's, Somers said she had long been an admirer of the brand and its digital leadership and the creative bar the marketing team have set in the industry.