The appointment comes as the social network’s valuation hit US$18bn (£11.8bn) and membership numbers surpassed 200 million globally and 11 million in the UK.
As well as general corporate and reputation building, Firstlight will raise LinkedIns profile among recruiters and marketers promoting the audience insights it can offer.
The agency will target trade press, demonstrating the insights the network can offer through its talent solutions, which connects employers and employees, and its marketing solutions, which connects brands and users.
Previously corporate and trade PR was handled in-house with agencies called in for project work. Firstlight will work closely with LinkedIn’s EMEA corporate comms director Ngaire Moyes, and corporate comms manager Richard George, as well as Splendid, which was brought in last year to handle consumer PR.
LinkedIn has introduced several features over the past year, including an improved mobile site and an influencers’ platform with updates from top professionals such as Richard Branson and Barack Obama.