Before she became known as “America’s Mom” on “The Brady Bunch,” Florence Henderson was an established Broadway star and a frequent presence on television as a singer, a member of NBC’s “Today” show team and the first female guest host of “The Tonight Show.”

But it was for her role as Carol Brady, the calm, problem-solving, yet stylish mother of “The Brady Bunch,” a sitcom about a blended suburban family, that Ms. Henderson became one of the most popular actresses on television.

She died Nov. 24 at a Los Angeles hospital at age 82. Her unexpected death was attributed to “heart failure,” her manager, Kayla Pressman, said in a statement.

Earlier in the week, Ms. Henderson had attended a taping of ABC’s “Dancing With the Stars” to cheer on Maureen McCormick, who played her daughter Marcia Brady on “The Brady Bunch.” In 2010, when she was 76, Ms. Henderson had been one of the oldest contestants on “Dancing With the Stars.”

“The Brady Bunch,” which also starred Robert Reed as a widowed father of three boys, ran on ABC-TV from 1969 to 1974. The show never cracked the top 25 in ratings, but through continual reruns it attracted a strong following in later years and became an unexpected cultural touchstone.

“If you’re anywhere between 40 and 60, chances are you know that show — you couldn’t avoid it,” Robert Thompson, a scholar of television and popular culture at Syracuse University, said Friday in an interview.

Ms. Henderson’s character was memorably introduced at the beginning of the show’s jaunty theme song: “Here’s the story of a lovely lady who was bringing up three very lovely girls. All of them had hair of gold, like their mother, the youngest one in curls.”

As the six children of “The Brady Bunch” struggled to adapt to sibling rivalry and teenage awkwardness, Ms. Henderson’s character was the sensible, reassuring presence that held the household together.

“She was so understanding, never lost her temper,” Thompson said. “If I were to make a pantheon of TV moms, I would put Carol Brady near the top.”

It was never revealed whether Ms. Henderson’s character was divorced or widowed, and the wholesome show seldom delved into the divisive social issues that seeped into other sitcoms of the period. Instead, “The Brady Bunch” was firmly in the tradition of earlier family series such as “Leave It to Beaver,” “The Donna Reed Show” and “Father Knows Best.”

During the first season of “The Brady Bunch,” Ms. Henderson encapsulated the show’s inclusive sense of family warmth by consoling Bobby, the youngest son of the newly united family. She told him not to think of himself as a stepchild.

“Listen, the only steps in this house are those,” she said, pointing to the staircase, “the ones that lead up to your bedroom.”

Comic relief was provided by the family housekeeper, Alice, played by Ann B. Davis.

After “The Brady Bunch” was canceled in 1974, Ms. Henderson appeared in a series of spinoffs and TV movies, including “The Brady Brides,” “A Very Brady Christmas,” “The Bradys” and “The Brady Bunch Hour.”

The show’s reruns unexpectedly caught on with a new generation of viewers, many of whom saw it as a form of camp, complete with the outlandish hair and clothing styles of the early 1970s.

“Unlike real life, the Bradys’ problems were always solved in 30 minutes,” Ms. Henderson said in 1990. “I think that show had a little magic charm about it.”

Florence Agnes Henderson was born Feb. 14, 1934, in Dale, Ind., the youngest of 10 children. She grew up in poverty on a tobacco farm near Owensboro, Ky.

By the time she was 4, Ms. Henderson later recalled, “My mother would send me to the store to get groceries, and they’d give them to me if I would sing.”

At 17, she moved to New York to study singing and acting and within a year was a chorus member on Broadway. In 1952, composer Richard Rodgers chose her for the lead role of Laurey in a touring production of “Oklahoma!” A year later, she starred in a Broadway revival of the acclaimed musical.

“She is the real thing, right out of a butter churn somewhere,” critic Walter Kerr wrote in the New York Herald Tribune.

In 1959, Ms. Henderson became a regular on NBC’s “Today” show, giving reports on fashion and the weather. She toured in the role of Maria in “The Sound of Music” in 1961, then a year later became the first woman to sit in as a guest host of “The Tonight Show.”

Ms. Henderson temporarily lost her hearing in the 1960s as the result of a hereditary condition that was corrected by surgery. She appeared on countless TV variety shows and game shows and made commercials for Wesson cooking oil for more than 20 years.

In a 2011 memoir, “Life Is Not a Stage: From Broadway Baby to a Lovely Lady and Beyond,” Ms. Henderson quashed an oft-repeated rumor that she had an affair with Barry Williams, the teenaged actor who played Greg on “The Brady Bunch.” In fact, when Williams got married, she sang at his wedding.

Ms. Henderson’s first marriage, to theater producer Ira Bernstein, ended in divorce. Her second husband, John Kappas, a hypnotherapist who helped her overcome her stage fright and fear of flying, died in 2002. (Ms. Henderson also became a licensed hypnotherapist.)

Survivors include four children from her first marriage and five grandchildren.

In 1999, Ms. Henderson rejoined NBC for a year as a host of “Later Today.” She also had a cabaret act, continued to appear in stage, TV and movie productions and, at the time of her death, had a cooking show on the RLTV cable network.

But she remained happily resigned to her best-known role as the soothing mother with all the right answers on “The Brady Bunch.”

“I think we represented a family who really cared about each other,” she said. “I think everyone dreams of that, whether they have it or not.”