Joseph B. Flavin, chairman and chief executive officer of the Singer Company, died yesterday at Norwalk Hospital. He was 58 years old and lived in New Canaan, Conn.

Mr. Flavin joined Singer in 1975 and oversaw its evolution from the world's best-known manufacturer of sewing machines to a military contractor.

At the start of his tenure, critics were saying that Singer had spread itself too thin. One big problem was the company's plunge into the making of electronic cash registers for department stores and supermarkets. Mr. Flavin, who was regarded by many on Wall Street as an astute planner and an expert in doing business abroad, quickly pulled Singer out of business machines and began restructuring the rest of the company. An Overhaul of Its Identity

Last year he even spun off the sewing machine business, which had been the essence of the company's identity from the time it was founded in 1851. As he acknowledged in a 1984 interview, what had begun in the mid-1970's as a gradual retreat from unprofitable sidelines turned into an overhaul of the company's identity.

''This is a company whose whole culture was built around the sewing machine,'' Mr. Flavin said then. ''As hard as we tried, that couldn't be changed overnight.''

Mr. Flavin's efforts left Singer a streamlined technology company that draws 80 percent of its revenue from aerospace electronics.

Soon after joining Singer, Mr. Flavin recognized that social and economic forces were causing a rapid decline in the United States sewing machine market. Chief among these was an increase in the number of women with full-time jobs. Another factor was the increasing availability of lower-priced imported clothing, which reduced consumers' need to repair old or damaged clothes.

By 1979, when the full extent of Singer's troubles had become clear, Mr. Flavin took action to trim the company's losses. Singer closed its two major sewing machine plants. One was in Elizabeth, N.J., the other in Scotland. At the same time, the company shifted its sewing machine manufacturing to plants in Taiwan and Brazil, where labor costs were less expensive.

The company also closed or sold its 1,600 retail sewing machine stores to independent dealers.

In Mr. Flavin's 12 years as head of Singer, the company's headquarters were moved twice, from 30 Rockefeller Plaza in Manhattan to Stamford, Conn., in 1978, and from Stamford to Motvale, N.J., last year.

In August the Texas investor T. Boone Pickens announced that he had 4.4 percent of Singer's stock. Mr. Pickens's investment company, Mesa Partnership Ltd., said at the time that it might buy as much as 15 percent of Singer.

Mr. Flavin, who was born on Oct. 16, 1928, received a bachelor's degree in business administration from the University of Massachusetts in 1953 and a master of science degree from the Columbia University Graduate School of Business four years later. He also studied at the International Business Machines Corporation's executive school and the Williams College program in American studies for executives.

In 1978 he was awarded an honorary doctor of laws degree from the University of Massachusetts. Tenure With Xerox

Before joining Singer, Mr. Flavin was president of international operations as well as a director of the Xerox Corporation. He had joined Xerox in 1967 as vice president and controller and was promoted rapidly.

Mr. Flavin also spent 14 years at I.B.M.'s world trade division and was controller from 1965 to 1967.

He was a director of Pfizer Inc. and the New York Stock Exchange and a trustee of Northwestern Mutual Life Insurance Company.

He is survived by his wife, Melisande; a son, Patrick, and a daughter, Shawn, both of New Canaan, and six grandchildren.

Shawn E. Flavin, daughter of Mr. and Mrs. Joseph B. Flavin of New Canaan, Conn., was married yesterday afternoon at her parems' home, to Roy Dallas Russell, son of Mr. and Mrs. A. Lewis Russell of Sarasota, Fla., formerly of Stamford. Conn.

The Rev. Thomas S. Fitzgerald, president of Fairfield University, performed the ceremony.

Mr. Flavin is executive vice president of the Xerox Corporation and president of its international operations. The bridegroom's father, who is retired, was director of industrial security for the Exxon Corporation.

Mrs. Patrick Flavin, sisterin‐law of the bride, was matron of honor. The bridesmaids were the Misses Becky Russell, sister of the bridegroom, and Ellen Scanlan. Nicole Noël Flavin, niece of the bride, was flower girl. Bart van Rees was best man.

Mrs. Russell graduated from Trinity College in Hartford. She is a third‐year student at the New York Medical College, as is her husband, who is a University of Connecticut graduate.