Philip M. Foisie, a senior editor at The Washington Post for the past 25 years, was named executive editor of the International Herald Tribune yesterday. The announcement of the appointment was made at the newspaper's headquarters in Paris by its publisher, Lee W. Huebner.

Foisie, 59, became the Post's assistant managing editor in charge of foreign news in 1968 and was responsible, Huebner said in his announcement, "for the creation and expansion of the Post's foreign desk and network of foreign correspondents. There are few newsmen who are as steeped in international journalism."

The International Herald Tribune is owned jointly by The New York Times Co., Whitney Communications Corp. and The Washington Post Co. The newspaper, published in Paris, has printing sites in Paris, London, Zurich and Hong Kong and has a daily paid circulation of over 140,000 copies distributed in 143 countries.

"Phil Foisie's role in the growth of this newspaper has been vital and constant," Benjamin C. Bradlee, executive editor of The Washington Post, said, "and the Trib is lucky to have him."

Foisie will be replaced as assistant managing editor for foreign news by Jim Hoagland, currently the Post's foreign editor, and Karen DeYoung becomes foreign editor correspondents for the Post.

Huebner also announced that Walter N. Wells will serve as editor of the International Herald Tribune under Foisie's direction. Wells worked for seven years with the Richmond Times-Dispatch before moving to The New York Times in 1972. He has been at the International Herald Tribune for one year.