Dorrian's move within the international brand and digital agency will see him focus on regional development across Greater China and Asia.
He has worked as creative director in London for five years and takes up his new role in Hong Kong on September 7.
He will work with Start's regional clients, which includes Beijing property outfit Modern Green, working to develop the company as a leading creative force in the region.
He will work alongside Jonathan Cummings, Start Creative Hong Kong’s managing director.
Cummings described Dorrian as an exceptional creative with a proven track record of developing young talented graduates who have gone on to become outstanding designers.
Cummings said: "There is no shortage of raw creative talent in Hong Kong and across the region, and I am very much looking forward to working with Michael to unlock their potential and delivering exciting work for our clients."
Start Creative Hong Kong is the Asia hub of Start Creative, which is headquartered in London with offices in Dubai and Mumbai.
Recent projects include the development of retail communications for the Adidas global flagship store in Beijing last year.
Clients include Air Asia, Barclays and a number of Virgin Group companies.