Exposure, the creative marketing services group, bought the FMCG and brand partnership specialist for an undisclosed amount.
The 25-strong agency has moved into Exposure's Little Portland Street complex but will continue to operate as a separate brand. No redundancies will be made.
Exposure's joint CEO Tim Bourne said it was his intention to buy the entire business in the future, although a date has not been fixed.
While 360 Communications and Exposure will cross-sell creative services such as digital, the PR teams will not work together on briefs.
'One of the reasons we have bought 360 is to give us the opportunity to work in sectors where we cannot do so as Exposure because we have exclusivity contracts,' said Bourne.
Last week Exposure resigned its Red Bull account due to growing conflict with existing client Coke. Pretty Green, the agency set up by former Exposure MD Mark Stringer, picked up the business instead (PRWeek, 31 October).
Bourne said he did not rule out buying other PR agencies, but that if he did it again 'we'd acquire and merge' rather than keep separate brands.
360 Communications was founded by Katie Rowen and Alison Saunders, former Edelman staffers.