The agency, with its creative arm Flint, has also picked up the creative and media for Travelex's travellers cheques service with Barclays Bank.
BLM won the Suzuki brief after a pitch against two other agencies. TV activity is likely to begin in the early autumn.
Suzuki's press planning and buying account will remain with Media by Design.
The £4 million TV spend will form part of Suzuki's £10 million spend. Last year Suzuki spent just 10 per cent of its media budget on TV, with the rest on outdoor activity. It began its advertising activity this year with a press and poster campaign to support its Liana hatchback model. The creative was through Nexus/H UK, with media through Media by Design.
David Seward, Suzuki's director of sales and marketing (automobile division), said: "BLM was chosen because it demonstrated an understanding of how we could get the best value from our investment in television."
Paul van Barthold, the managing director of BLM Media, said: "This is a major win for BLM. Suzuki is a great brand name and we are looking forward to working with it to build its success in the UK."
BLM Media's Travelex win will initially involve creative and media for a national poster campaign.
Travelex supplies travellers cheques and foreign money through Barclays.
Creative uses the line: "Notes from a small island: take Visa travellers cheques."
Flint, BLM's creative arm, launched a year ago.