They are joining BBH from M&C Saatchi, where the duo worked on campaigns for British Airways, Cabnumbers.com and Holmes Place.
The executive creative director at BBH, John O'Keeffe, said: "Tom and Kit like doing simple, award-winning stuff that works. They'll fit in here."
Spicer, 32 and Dayaram, 26, teamed up at M&C Saatchi in 2002. Their most notable work at the agency was for Transport for London. They created the "don't die before you live" campaign, which centred on two fictional Hollywood lives.
One ad told the rags-to-riches story of Sarah Rivers, and was styled on the Cribs show. As the spot progresses, it becomes clear it is just a vision of what might have been, for Sarah is actually a teenage pedestrian about to be killed while crossing the road. It won Silver and Bronze Arrows at the 2005 BTAA.
These appointments follow three other signings O'Keeffe made to the creative department in August. The agency hired the former executive creative director of Mustoes, Mick Mahoney, as a creative director, as well as Nick Allsop and Simon Veksner, who were behind DDB London's "cops" ad for Volkswagen Polo.