He replaces Steph Johnson, who has headed the North American division since its New York office opened in 2010.
Hamilton, former US editor of Incisive Risk Waters, has worked in both agency and in-house PR roles including vice-president of financial services comms agency Intermarket and director of PR at Javelin Technologies.
Alastair Turner, global CEO at Aspectus, said: "Jed has varied experience across multiple sectors. But he particular impressed us with his track record in financial services and technology.
"As a former journalist and editor he has great news sense, is a terrific content producer and has fantastic relationships across our key sectors. But more than that, he shares our vision for a fully integrated approach to comms, embracing visual and written content, all forms of media and search engine marketing."
Hamilton said: "I was immediately attracted by the opportunity to take on a leadership role with such a dynamic and progressive agency as Aspectus."
Aspectus employs 12 people at its New York office. The company’s other venture in the US is a partnership with Paige PR in Houston.
Aspectus is ranked 79th in PRWeek UK’s Top 150 agencies report, with a fee income of £2.4m in 2014. Last month the firm's London office moved from Holborn to Old Street's 'tech city'.