Brown died Monday at a hospital in New York after a brief hospitalization, Hearst CEO Frank A. Bennack, Jr. said in a statement.
"Sex and the Single Girl," her grab-bag book of advice, opinion, and anecdote on why being single shouldn't mean being sexless, made a celebrity of the 40-year-old advertising copywriter in 1962.
Three years later, she was hired by Hearst Magazines to turn around the languishing Cosmopolitan and it became her bully pulpit for the next 32 years.
She said at the outset that her aim was to tell a reader "how to get everything out of life -- the money, recognition, success, men, prestige, authority, dignity -- whatever she is looking at through the glass her nose is pressed against."
"It was a terrific magazine," she said, looking back when she surrendered the editorship of the U.S. edition in 1997. "I would want my legacy to be, `She created something that helped people.' My reader, I always felt, was someone who needed to come into her own."
Along the way she added to the language such terms as "Cosmo girl" -- hip, sexy, vivacious and smart -- and "mouseburger," which she coined first in describing herself as a plain and ordinary woman who must work relentlessly to make herself desirable and successful.
She put big-haired, deep-cleavaged beauties photographed by Francesco Scavullo on the magazine's cover, behind teaser titles like "Nothing Fails Like Sex-cess -- Facts About Our Real Lovemaking Needs."
Male centerfolds arrived during the 1970s -- actor Burt Reynolds' (modestly) nude pose in 1972 created a sensation -- but departed by the `90s.
Brown and Cosmo were anathema to militant feminists, who staged a sit-in at her office. One of them, Kate Millet, said, "The magazine's reactionary politics were too much to take, especially the man-hunting part. The entire message seemed to be `Seduce your boss, then marry him."'
Another early critic was Betty Friedan, who dismissed the magazine as "immature teenage-level sexual fantasy" but later came around and said Brown, "in her editorship, has been a rather spirited and gutsy example in the revolution of women."
"Bad Girls Go Everywhere," the 2009 biography of Brown by Jennifer Scanlon, a women's studies professor, argued that her message of empowerment made Brown a feminist even if the movement didn't recognize her as such.
There was no disputing that Brown quickly turned a financial turkey into a peacock.
Within four issues, circulation, which had fallen below the 800,000 readers guaranteed to advertisers, was on the rise, even with the newsstand price increasing from 35 cents to 50 and then 60.
Sales grew every year until peaking at just over 3 million in 1983, then slowly leveled off to 2.5 million at $2.95 a copy, where it was when Brown left in 1997. (She stayed on as editor in chief of the magazine's foreign editions.)
She was still rail-thin, 5-feet-4 and within a few pounds of 100 in either direction, as she had kept herself throughout her life with daily exercise and a careful diet.
"You can't be sexual at 60 if you're fat," she observed on her 60th birthday. She also championed cosmetic surgery, speaking easily of her own nose job, facelifts and silicone injections.
An ugly duckling by her own account, Helen Gurley was a child of the Ozarks, born Feb. 18, 1922 in Green Forest, Ark. Growing up in the Depression, she earned pocket money by giving other kids dance lessons.
Her father died when she was 10 and her mother, a teacher, moved the family to Los Angeles, where young Helen, acne-ridden and otherwise physically unendowed, graduated as valedictorian of John H. Francis Polytechnic High School in 1939.
All the immediate future held was secretarial work. With typing and shorthand learned at a business college, she went through 18 jobs in seven years at places like the William Morris Agency, the Daily News in Los Angeles, and, in 1948, the Foote, Cone & Belding advertising agency. There, when finally given a shot at writing ad copy, she began winning prizes and was hired away by Kenyon & Eckhardt, which made her the highest paid advertising woman on the West Coast.
She also evidently was piling up the experience she put to use later as an author, editor and hostess of a TV chit-chat show.
"I've never worked anywhere without being sexually involved with somebody in the office," she told New York magazine in 1982. Asked whether that included the boss, she said, "Why discriminate against him?"
Marriage came when she was 37 to twice-divorced David Brown, a former Cosmopolitan managing editor turned movie producer, whose credits would include "The Sting" and "Jaws."
Her husband encouraged Brown to write a book, which she wrote on weekends, and suggested the title, "Sex and the Single Girl."
They moved to New York after the book became one of the top sellers of 1962. Moviemakers bought it for a then-very-hefty $200,000, not for the nonexistent plot, but for its provocative title. Natalie Wood played a character named Helen Gurley Brown who had no resemblance to the original.
She followed up her success with a long-playing record album, "Lessons in Love," and another book, "Sex in the Office," in 1965.
That year she and her husband pitched a women's magazine idea at Hearst, which turned it down, but hired her to run Cosmopolitan instead.
In 1967 she hosted a TV talk show, "Outrageous Opinions," syndicated in 19 cities and featuring celebrity guests willing to be prodded about sex and other risque topics.
She also went on to write five more books, including "Having It All" in 1982 and in 1993, at age 71, "The Late Show," which was subtitled: "A Semiwild but Practical Survival Plan for Women Over 50."
"My own philosophy is if you're not having sex, you're finished. It separates the girls from the old people," she told an interviewer.
The Browns were childless by choice, she said.
Rayner Pike contributed to this report.