Hamilton is a former senior adviser to Labour deputy leader Tom Watson and has also been a policy adviser and speechwriter to to the party for several years, helping prepare Ed Miliband, Harriet Harman and Jeremy Corbyn for Prime Minister's Questions.
He is the co-author of Punch & Judy Politics: An Insiders’ Guide to Prime Minister’s Questions.
Hamilton will report to James Gurling and Jamie Lyons, the joint heads of MHP’s Public Affairs practice.
Lyons said Hamilton’s appointment reflects growing interest from clients about what a potential Labour Government would mean for their businesses.
"As one of the most experienced and recent Labour advisers working in our industry, there is nobody better placed to tell them," Lyons said.
"Tom is joining MHP at a great time. We are growing rapidly, winning a host of exciting new clients and investing in a number of major new hires to further strengthen our team."
MHP Communications is the latest agency to take on Labour Party veterans to bolster public affairs practices.