McGettigan will join Christopher Peacock, a former local councillor and mayor in the Bolton area of Greater Manchester, who will lead the agency's public affairs offer in the city.
The expansion includes additional hires to Grayling's Manchester premises, taking its total headcount in Manchester and Leeds to 12.
Grayling's northern team will offer clients the same full-service offering as its London HQ, including consumer brand, corporate, public affairs, experiential and digital services.
Grayling Manchester will support clients including Marks & Spencer, Visa and HSBC, while recent wins Eurovia UK, Mookie Toys and One Manchester will be serviced from both the Manchester and Leeds offices.
The northern network will also be supported the firm's central creative services team, IGNITE, led by head of strategy and planning Nathan Kemp.
Grayling UK managing director Jonathan Curtis said: “With nine offices across the UK we’ve always believed in a Britain beyond [TfL] Zone 1, and with the government’s 'levelling up' agenda, now couldn’t be a more exciting time to be continuing to invest in our network."
McGettigan said: “I believe that with Grayling’s commitment to establishing a full-service Manchester agency, coupled with our unique ability to tap into our unrivalled UK-wide network, we can truly offer something new and different."
“This is the kind of investment we welcome to strengthen the quality of communications being delivered in the region for regional businesses and beyond," added Henri Murison, director of the Northern Powerhouse Partnership.