The MGA, which will be known as Stabilis, will provide insurance policies exclusively through the broker, with an initial focus on private motor insurance.
Sure Thing said the venture puts the firm in a “prime position to grow policy count and revenue” and complements its existing broker panel.
Stabilis will be overseen by chief executive Kevin Kiernan, formerly of Groupama and Ageas, along with pricing director Matt Fothergill, who previously held roles with EMB and Tesco Underwriting.
Sure Thing chief executive Brendan Devine is to take on a non-executive director role at the new venture.
Devine said: “This is a great day for the business and our employees.
“We’ll be focusing on the private car insurance market to begin with, but with a clear directive and ambition to grow the business and add significant scale and value to the group.
“As well as benefiting from the experience and expertise of the Sure Thing team, the new business has developed a state of the art, bespoke system and pricing hub.”
Kiernan added: “I’m proud to be working with such a forward thinking and innovative group and look forward to driving significant growth.”