The agency's first task is to create a new brand positioning for Everest as its looks to extend its portfolio beyond windows and into all areas of home improvement.
The pitch was led by Stephen Maher, the chief executive officer of MBA, and Graham Kerr, its creative director.
The AAR acted as the intermediary while the media is handled by BBV&S.
The appointment marks a return to brand activity from the double-glazing and home security company.
Duncan Bland, the marketing director at Everest, said: "We are delighted to be working with the team at MBA. Moving the Everest brand on to a new and exciting future is no easy task and MBA's considered and well-researched approach gave us the confidence to select it."
Maher added: "We are proud to be working with one of the UK's great brands."