Beam, based in London's Clerkenwell, was set up by founder Jane Leah in 2002.
The agency's five employees will be based in Talk PR's headquarters at Rathbone Place from 3 January. No redundancies were made and the combined agency will employ 53 people.
Talk PR, which is part of the M&C Saatchi group, has acquired a majority interest in Beam and will now set up a division called Talk Technology.
All of Beam's current clients will remain, as there have been no conflicts. These clients include Fujifilm and Griffin Technology.
Leah will head up the new division in Talk PR, reporting to COO Ryan Woor. She said: 'I'm looking forward to being part of a group that has a European network that we can tap into - before I could never offer clients that or go for new business in Europe.'
Talk PR CEO Jane Boardman said the M&C Saatchi group saw particular growth potential in the tech sector.
She added Talk PR had seen synergy between Beam's accounts and its core business made up of lifestyle, fashion and beauty clients.
Both parties declined to comment on how much the deal was worth but did say that the combined projected fee income of the combined agency would be £4m in 2012.