Allison+Partners – which has 29 offices and 400 staff across the US, Asia Pacific and Europe – has added OneChocolate to expand its reach in Europe, said global CEO Scott Allison.
The agency last year recorded revenues of $52.28m (£39.82m), up 19 per cent on the previous year.
It has been making changes to its leadership structure, which included promoting Jonathan Heit to global president in June.
OneChocolate is headquartered in London, but also has offices in Munich and San Francisco and has worked with clients including Nokia, Playmobil UK, Disney and Panasonic.
"There are synergies across the board with Allison+Partners – OneChocolate’s approach to storytelling, digital expertise, focus on measurement and philosophy on creating a collaborative and supportive culture couldn’t align anymore perfectly with ours," said Allison.
"As we continue to expand our operation in London and throughout Europe, we’re proud to welcome OneChocolate to the A+P family, and excited to offer our global network and capabilities to add opportunity and value to its clients and staff."
OneChocolate founders Jill Coomber and Sue Grant will join A+P’s European management team, with Coomber becoming managing director of A+P’s consumer practice and Grant appointed as managing director of the technology practice in Europe.
The pair founded the agency in 1992, and Grant said they were looking for "new challenges and opportunities", leading to a year of negotiations to finalise the deal.
"The opportunities at both the local and international levels are exactly what we were looking for," added Coomber. "Working on our next five year plan, a big objective was to grow further and faster in Europe."
Allison+Partners is organised around six practices: consumer marketing, corporate, global China, healthcare, public affairs and technology, and has worked with clients including Toyota and Dignity Health.