Brilliant had been one of the biggest independent agencies left and has three offices across Leeds, Manchester and Birmingham and picked up the account for the re-launch of the car marque MG in April this year.
The deal went through last night but further details are yet to emerge.
Brilliant Media had a tough start to 2011 after losing the TV, radio, outdoor and digital business for DFS, worth around £40m in billings, to MediaCom, and the £12m Asda regional media business to Carat.
There has been a lot of change in the regional agency market this year. Aegis Media bought the Manchester-based media agency MediaVest in July for an initial payment of £27m, which could rise to as much as £95m depending on future performance.
Aegis Media rebranded MediaVest as Carat Manchester and then last month rebranded its Feather Brooksbank agencies to Carat, folding the Manchester office into the former MediaVest agency.