She was 97.
She had celebrated her 97th birthday just last month with nearly 300 fans who gathered in Carmel to celebrate with her.
Day had recently contracted a serious case of pneumonia which resulted in her death, the foundation said.
Day was arguably the top female box-office star in Hollywood history, with a No. 1 ranking in 1960, 1962, 1963 and 1964. She had her first hit as a big-band vocalist during World War II before making nearly 40 movies in the next two decades, reigning supreme at a time when her contemporaries included Audrey Hepburn, Marilyn Monroe and Elizabeth Taylor.
Sex comedies such as "Pillow Talk," "Lover Come Back" and "That Touch of Mink" established her as a sunny but slightly uptight career woman who fought off men's advances.
"My public image is unshakably that of America's wholesome virgin, the girl next door, carefree and brimming with happiness. An image, I can assure you, more make-believe than any film part I ever played," Day told A.E. Hotchner in her memoir, "Doris Day: Her Own Story."
Or as one-time co-star Oscar Levant famously joked, "I knew Doris Day before she was a virgin."
The chaste screen persona seemed at odds with her private life.
She married four times and had a child before she was 20. She described her first husband as a "psychopathic sadist" who beat her. Her second husband told her by letter that he was leaving her after eight months. Husband No. 3 was agent Martin Melcher, who mismanaged her fortune and left her in debt when he died. Her fourth, restaurateur Barry Comden, complained to the press that she kicked him out of bed for her pets.
Day also suffered from panic attacks in the early '50s, what she later described as "tantamount to a nervous breakdown."
As singer, one of 'the best in the business'
She was born Doris Mary Ann von Kappelhoff on April 3, 1922, in Cincinnati.
She dreamed of a career as a dancer until she injured her right leg in a car accident as a teenager. During a long convalescence, she immersed herself in the big-band sounds of Tommy Dorsey and the vocals of Ella Fitzgerald.
She soon became a performer on local radio and then joined a swing band. The bandleader feared that her last name, Kappelhoff ("von" had been dropped), was too long for a marquee, so he dubbed her Doris Day after a song of hers, "Day After Day."
"But I never did like it. Still don't. I think it's a phony name," Day said more than 30 years later.
Her blonde good looks and smooth, velvety voice ensured that she quickly moved up the musical ranks. As a singer in Les Brown's band, she scored a hit with "Sentimental Journey," a defining ballad for servicemen returning from World War II.
Brown said later, "I'd say that next to Sinatra, Doris is the best in the business on selling a lyric."
Day would record more than 600 songs and nearly 30 albums, including such hits as "It's Magic," "Secret Love," "Que Sera, Sera" and "Everybody Loves a Lover" and concept albums such as 1956's "Day by Day" and 1957's "Day by Night." As recently as 2011, her album "My Heart" made the UK Top 10. She received a Grammy Lifetime Achievement Award in 2008.
Rising star, falling into formula
Her singing popularity led to a movie debut in 1948 in "Romance on the High Seas" and a contract at Warner Bros. Her early peak came in the 1953 Western musical "Calamity Jane."
After her contract ended, she entered the most fruitful period of her career, including dramatic parts in "Love Me or Leave Me," opposite James Cagney, and in Alfred Hitchcock's "The Man Who Knew Too Much," starring James Stewart.
Day turned almost exclusively to comedies by the late '50s. "Pillow Talk" and "Lover Come Back" opposite Rock Hudson and "That Touch of Mink" with Cary Grant cemented her goody-two-shoes reputation, if sometimes unfairly: The films were about Day, usually cast as an independent working woman, resisting her leading man's charms because she'd been deceived more than to protect her virginity.
Though the increasingly formulaic films were successful, they'd prove to be Day's undoing and make her passé when the counterculture supplanted the "Mad Men" era.
In a review of her last film, 1968's "With Six You Get Eggroll," Vincent Canby summed up the critical attitude toward Day then, noting that there were "some hints of the very real comic talent that has, over the years, become hermetically sealed inside a lacquered personality, like a butterfly in a Mason jar."
She had a chance to change course when director Mike Nichols offered her the role of Mrs. Robinson in "The Graduate," but the star wasn't interested. "I could not see myself rolling around in the sheets with a young man half my age whom I'd seduced," she recalled later. "I realized it was an effective part ... but it offended my sense of values."
With his wife's film career in decline due to mediocre movies he initiated, husband Melcher began to explore options on TV despite her opposition. A perfectionist, Day feared the medium's quick production pace.
Melcher died unexpectedly in 1968, leaving Day with a CBS sitcom and in financial straits. Her husband's reliance on attorney Jerome Rosenthal for business advice proved disastrous: The lawyer went through Day's millions with bad investments in oil wells, cattle and hotels.
"I don't know if Marty betrayed me or not. I tend to think he didn't betray me. I think he loved me," she told the Los Angeles Times two decades later about her husband's management.
"The Doris Day Show" proved to be a lifesaver. Despite an ever-changing format, it ran for five seasons, gave her financial stability and kept her working as she coped with the loss of her spouse of 17 years. Day sued Rosenthal for mismanagement and won a $20 million-plus verdict in 1974 after years of litigation (she later settled with insurers).
Activist for animals
By the mid-'70s, she withdrew from the limelight to focus on animal rights and set up the Doris Day Animal League and Doris Day Animal Foundation. In a 2012 interview with "Fresh Air" host Terry Gross, Day admitted that she had about 30 dogs at one point.
"All my life, I have never felt lonely with a dog I loved at my side, no matter how many times I've been alone," she said in her memoir.
As a staunch advocate for animals, she briefly came out of retirement to host a cable TV pet show called "Doris Day's Best Friends," which included an emotional reunion with three-time co-star Hudson shortly before his death in 1985.
Perhaps her closest friend, son Terry Melcher, a music producer, died in 2004 at 62. He was survived by his son, Ryan.
There was talk of comebacks: She reportedly was offered "Murder, She Wrote" and the Debbie Reynolds role in "Mother" in 1996. But she resisted Hollywood overtures. In 2015, she batted down reports she was to appear in a Clint Eastwood film.
During her career and retirement, Day always seemed to adhere to the philosophy of her biggest hit, "Que Sera, Sera," which she initially opposed as a "kiddie song" but which became her signature tune.
"Que sera, sera.
Whatever will be, will be;
The future's not ours to see.
Que sera, sera,
What will be, will be."
Reaction to her death poured in from Hollywood.
"Condolences to the family of Doris Day," actor William Shatner tweeted. "She was the World's Sweetheart and beloved by all. Que Será, Será!"