The agency, on an initial two year contract will provide strategic counsel and support to the WSTA with campaigns, PR, policy and media engagement.
It has also been briefed to support the association's corporate social responsibility priorities to promote responsible drinking and challenge alcohol-related crime.
MHP’s MD James Gurling and head of media Ian Kirby will provide senior advice.
Gurling said: "We will be working right across our integrated corporate affairs team, which brings together significant expertise in delivering communications for clients like the WSTA."
The incumbent agency was Tetra Strategy.