Smith was born on August 24, 1949, in the Pittsburgh suburb of Everson, Pennsylvania. Her mother, Florence, was a maid and her father, William, a steelworker. Smith was raised in Scottdale, Pennsylvania, and attended Southmoreland High School, being graduated in 1967.

In the mid-1960s, Smith began her career in modeling, participating in the Ebony Fashion Fair and later signing with the Wilhelmina Models agency. Smith was the first African-American model to be featured on the cover of Mademoiselle magazine in 1976.

Smith owned multiple restaurants called B. Smith. The first opened in 1986, on Eighth Avenue at 47th Street in New York City, and several years later moved around the corner to Restaurant Row on 46th Street; followed by another one in Sag Harbor, Long Island, New York. She also owned a restaurant in the historic Beaux-Arts Union Station in Washington, D.C.; in September 2013, it was reported that restaurant would close. In 2014, the Sag Harbor restaurant was shuttered, followed by the Manhattan location in January 2015.

Smith married twice and although she had no biological children, she was stepmother to Dana Gasby. Her first marriage was to former HBO executive Donald “Don” Anderson from 1986 until 1990. Smith began dating Anderson after formally meeting him at her restaurant in late 1986. Smith married Dan Gasby in 1992 at St. Luke’s Lutheran Church in Manhattan. Gasby was the executive producer of the Essence Awards and the senior vice president of marketing at Camelot Entertainment Sales Inc. Smith was stepmother of Gasby’s daughter, Dana.

Smith made two appearances on Mister Rogers’ Neighborhood, once as a model for Queen Sara’s wedding dress, and once giving a tour of her restaurant, B. Smith, and making raspberry custard with Fred Rogers and her head chef, Henry. During the episode, she taught child viewers about the importance of washing hands, and shared the excitement of using huge bowls and mixers. She said her dream was to feed people, which began at an early age when she fed her dolls. Her weekly half-hour syndicated television show, B. Smith With Style, debuted in 1997 and also aired weekdays on BTN and Bounce TV. It featured home decor and cooking segments.

Smith’s interest in décor and restaurant design led to the development of her first home collection, which debuted at Bed, Bath & Beyond in Spring 2001. She also launched a line of serveware in 2004. In spring 2007, Smith debuted her first furniture collection with the La-Z-Boy company Clayton Marcus.

In June 2014, Smith revealed that she had been diagnosed with early-onset Alzheimer’s disease, stating that she came out with the information to counter the stigma associated with the disease. In November 2014, Smith’s husband reported her missing from Southampton, New York. She was found the next day in a cafe in Midtown Manhattan.

B. Smith authored three books concentrating on recipes and presentation: B. Smith’s Entertaining and Cooking for Friends (1995), B. Smith’s Rituals and Celebrations (1999), and B. Smith Cooks Southern Style (2009). Smith and her husband released Before I Forget in early 2016, detailing their journey following her diagnosis of early-onset Alzheimer’s. The book was written with husband Dan Gasby and Vanity Fair contributing editor Michael Shnayerson.

On February 22, 2020, Smith died of early-onset Alzheimer’s disease at age 70.