Barbara “B.” Smith, a steelworker’s daughter who became one of the top black models on magazine covers in the 1970s and later parlayed her glamour and personality into ventures as a restaurateur, TV host and lifestyle maven, died Feb. 22 at her home in East Hampton, N.Y. She was 70.

Her death was announced in a statement by her family. Ms. Smith was diagnosed in 2013 with early-onset Alzheimer’s disease and closed her restaurants — in Manhattan, on Long Island and at Union Station in Washington — over the next two years. She went on to champion Alzheimer’s research with her husband and caretaker, Dan Gasby, with whom she published a 2016 book, “Before I Forget.”

Ms. Smith — she shortened her first name to the initial “B.” during her modeling career — was widely regarded as a leading African American entrepreneur in fields that had long been unwelcoming to minorities.

She wrote books, started a magazine and had a syndicated TV show, all focused on entertainment and hostessing. Although her audiences transcended race, she often was described as a “black Martha Stewart.” Ms. Smith said she found the comparison “a little tired.”

“Martha Stewart has presented herself doing the things domestics and African Americans have done for years,” she once told New York magazine. “We were always expected to redo the chairs and use everything in the garden. This is the legacy that I was left. Martha just got there first.”

In her youth, Ms. Smith enjoyed cooking and sewing but felt unwanted at the 4-H club in her hometown in western Pennsylvania. To satisfy her budding interests, she once said, she founded a home economics club and named herself president.

After beginning her modeling career in Pittsburgh, Ms. Smith signed with the prominent Wilhelmina agency in New York. In 1976, she became one of the first black models to appear on the front of Mademoiselle magazine.

That cover, along with her frequent appearances in publications such as Ebony and Essence, launched a modeling career that took her to fashion capitals such as Paris and Milan — and to those cities’ top restaurants. Later, she tried to reproduce their menus at home for friends in the runway set.

Ms. Smith’s subsequent attempts at a pop-singing career fizzled, although to her credit as a tastemaker she hired the future soul star Freddie Jackson as a backup singer. She also tried to break into acting but found, she told New York magazine, that black actors were hired only to “play junkies or prostitutes or people who are left by junkies or prostitutes.”

Calling on her longtime passion for food, she became involved in the hospitality industry and worked her way into management at Ark Restaurants Corp. Partnering with that company, she opened her eponymous bistro in New York’s theater district in 1986.

A second B. Smith restaurant opened in Union Station in 1994; one critic called it “the grandest dining room on the Hill and maybe in the city.” Another followed in upscale Sag Harbor, N.Y., in 1998. Her cuisine often was described as high-end soul food. Some restaurant critics found that the establishments emphasized trendy decor over consistency in the kitchen, but they became popular social gatherings spots favored especially by black professionals.

“These were restaurants where you could say, we’re now investment bankers and lawyers and partners in consulting firms,” Lawrence Otis Graham, the author of “Our Kind of People: Inside America’s Black Upper Class,” told The Washington Post in a 2014 interview.

“You couldn’t bring clients and people you were trying to do business with to the old-fashioned mom and pop soul food restaurants that existed before her restaurants,” he continued. “She brought sort of a high-end polish to the soul food restaurant business.”

Ms. Smith’s business relationship with Ark Restaurants later soured, and she and her second husband, Gasby, eventually bought out their partner.

Her first book, “B. Smith’s Entertaining and Cooking for Friends” (1995), included plans for a cocktail party, a romantic Valentine’s Day meal, a beach picnic, an elegant soiree and a Kwanzaa-Christmas buffet.

Later volumes included “Rituals and Celebrations” (1999) and “B. Smith Cooks Southern-Style” (2009). Recipes included the ordinary (macaroni and cheese) and the gourmet (alligator-stuffed eggplant). “I’m not a chef,” she told The Post. “I’m a cook.”

In the 1990s, Ms. Smith launched the television show “B. Smith With Style,” which she hosted and was syndicated by Hearst Entertainment, and the magazine B. Smith Style. Her lifestyle empire came to include a furniture line and a collection at Bed Bath and Beyond.

“I felt we needed ideas that address a new generation,” she once wrote, “one too busy and creative for staid staples such as expensive caterers or gold-leaf calligraphy.”

Barbara Elaine Smith was born in Everson, Pa., on Aug. 24, 1949. Her father was a steelworker, and her mother, whom she credited with helping teach her to be a hostess, was a maid.

Ms. Smith said that she persuaded her father to allow her to enroll in the John Robert Powers modeling program only after she described it as a finishing school. One of her first jobs was as a ground hostess for Trans World Airlines at Pittsburgh International Airport.

As an aspiring model, she endured frequent rejections before being selected in 1969 for the Ebony Fashion Fair, a traveling fashion show, before signing with the Wilhelmina agency.

Her first marriage, to Donald Anderson, ended in divorce. Survivors include Gasby, whom she married in 1992, and a stepdaughter, Dana, both of East Hampton; and two brothers.

As Ms. Smith’s health and memory deteriorated in recent years, her husband began dating again, angering some of Ms. Smith’s followers even as he continued caring for her at home. Gasby told The Post last year that he had introduced his girlfriend to Ms. Smith, although it was unclear if she understood the nature of their relationship. “If ‘This Is Us’ and ‘Modern Family’ came together, it would be us,” he said.

Ms. Smith was a spokeswoman for various bath, cooking and kitchen products and, in 2011, appeared in “Love, Loss, and What I Wore,” an off-Broadway play written by sisters Nora and Delia Ephron based on a book by Ilene Beckerman about the place of fashion in women’s lives.

“Being a model is about fantasy,” Ms. Smith once said. “And so is entertaining.”

Harrison Smith contributed to this report.