The team of ex-theatrical set designers is led by creative designer Liz Marsh, with her company Liz Marsh Floral Design working as Inneventive's in-house florist.
Marc Davidson is the agency's creative event designer, and the new team will provide an additional event service to ensure all clients are looked after from the design process to the final execution of the event.
Inneventive has marquee venues at Hanover Square, at the Guards Museum opposite Buckingham Palace and at Sugar Quay on the Thames, overlooking the Tower of London, Tower Bridge and HMS Belfast.
It also organises the Frost Fair from 14-16 December, held outside the Tate Modern. Last year's event attracted 150,000 visitors.