The appointment means that fellow Bcom3 network Starcom will now be handling the Japanese agency's leading clients, including Canon, Toshiba, Nippon Paint and Nescafe, in addition to its own roster of clients, the most notable of which are Procter & Gamble, Coca-Cola and Mars.
It is believed that the move will increase Starcom's Hong Kong billings - currently estimated at US$100 million a year - by about 25 per cent.
Dentsu Hong Kong managing director, Morihiko Noguchi, described the merger as "a very positive move".
"Clearly, there is benefit in consolidating volume with Starcom, but more than that, Dentsu will now have access to Starcom's respected strategic planning tools, as well as gaining additional clout on the negotiation front. Starcom's experience in managing multiple agencies, as well as some of Hong Kong's largest agency of record assignments was also cited as a factor.
Noguchi, who took over as MD at the beginning of this year, also said that the new arrangement was part of a restructuring aimed at bolstering the local Dentsu office's capabilities, including creative.
Dentsu operates a specialist media unit across Asia-Pacific called Media Palette, including in Taiwan and China.
This unit, however, does not exist in Hong Kong, because, according to Noguchi, the market was not big enough.
"We have a media department within Dentsu, however, we decided that we should co-operate with Starcom in order to strengthen our overall capabilities, he said.
Dentsu's media staff is in the midst of merging with Starcom.
Starcom North Asia chief executive officer, Blaise D'Sylva, said: "We are looking at fit and resources as we bring the two entities together."