The agency won the account after a competitive pitch. It will be responsible for relaunching Unipart's 700-strong network of garages.
The 'You'll Find us Better' campaign will span online, radio and print advertising. Radio ads will launch across Heart and Real Radio networks using voices of Unipart Car Care Centres staff.
It will be the first time Unipart has advertised on this scale since the 1980s.
Stuart Sims, general manager, market planning and promotions at Unipart Automotive, said: "We are very excited about the prospect of relaunching the Car Care Centres with a consumer campaign designed to drive traffic into our nationwide network."
James Osborn, client services director at Nexus/H, said: "Through our integrated thinking we have developed a strategy and idea that we are confident will win hearts and minds to rightfully position Unipart Car Care Centres as a local and trusted brand."