Philip H. Geier Jr., whose binge of acquisitions as the chief executive of the Interpublic Group of Companies turned it into an advertising industry behemoth, died on June 19 in a hospice in Palm Beach, Fla. He was 84.

His death was confirmed by his daughter Hope Geier Smith.

Mr. Geier began his advertising career in the late 1950s as a trainee at McCann-Erickson, the ad agency that created memorable campaigns for clients like Coca-Cola, L’Oreal and General Motors. Under its former chairman, Marion Harper, McCann had become a conglomerate that offered its clients a wide breadth of advertising and marketing services. It changed its named to Interpublic in 1961.

But Mr. Geier (pronounced GUY-er) proved even more of an empire-builder than Mr. Harper. As Interpublic’s chairman and chief executive from 1980 to 2000, he oversaw the acquisition of nearly 200 companies, among them other ad agencies; public relations, lobbying and event planning firms; management consultants; and digital marketers. All were meant to fill the expanding needs of clients under a holding company model. Rivals like Omnicom, WPP and Publicis Worldwide also adopted the system.

“Interpublic was always a vision in Phil’s head,” Michael Sennott, a former vice chairman of McCann, said by phone. “As everybody was going global and television was penetrating the world, he wanted Interpublic to provide integrated communications in one spot.”