Gurling, who was awarded an OBE for political service in 2015, first worked in the party as a press aide to then leader Paddy Ashdown in the 1997 election.
He has also been a councillor, served on the party's federal executive committee, chairs its campaigns and communications committee, and worked with former leader Charles Kennedy. He was also the brother-in-law of Kennedy, who died in 2015.
Gurling has been at MHP since March 2014, having previously worked at Hanover, and before this held an in-house role at mobile network Three.
He will return to the agency after the election, an MHP spokesman said.
Gurling told PRWeek: "Anyone who has been involved in political campaigning and communication for as long as I have gets bitten by the election bug. So its really great to have the chance to chair such a great campaign team".
MHP also has another high-profile Lib Dem figure in its ranks - since early 2016, former energy secretary Ed Davey has been a senior adviser to the firm. Davey is not currently undertaking any work for MHP as he is campaigning to win back the Kingston & Surbiton parliamentary seat he lost in 2015.
Gurling returned to the MHP office on Friday for the first of a series of events branded the 'Floating Voter'. The agency set up a temporary pub and held a pub quiz and panel discussion, with Gurling joined by Twitter UK head of policy Nick Pickles, Sun journalist Lynn Davidson, and Ian Kirby, another MD at MHP, as host.