Reynolds made a name for herself as the girl-next-door lead of a string of hit musicals in the 1950s.
The 84-year-old suffered a stroke at son Todd Fisher's Beverly Hills home after telling him "I miss her so much, I want to be with Carrie," he was quoted as telling celebrity news website TMZ.
Reynolds made a name for herself as the girl-next-door lead of a string of hit musicals in the 1950s after being discovered by MGM studio bosses at a beauty contest in southern California, going on to earn her lone Oscar nomination for playing the title role in 1964's "The Unsinkable Molly Brown."
She is best remembered as sweet but shy voice artist Kathy Selden in "Singin' in the Rain" (1952) and holding her own despite being cast opposite tap-dancing superstar Gene Kelly, who was more than twice her age.
Off-screen, she was known as the wronged party in one of Hollywood's most notorious scandals, when her husband, singer Eddie Fisher, left her for her friend and fellow screen icon Elizabeth Taylor.
Reynolds' daughter Fisher, who catapulted to worldwide stardom as rebel warrior Princess Leia in the original "Star Wars" trilogy, died in Los Angeles on Tuesday, four days after suffering a heart attack on a transatlantic flight.
Media reports said Reynolds had been at her son's house to discuss funeral arrangements when she became ill.
Reynolds, who received the Academy's Jean Hersholt Humanitarian Award last year, was just 19 when she got her big break in "Singin' in the Rain," which celebrates Hollywood's transition from the silent era into "talkies."
Her 2013 autobiography "Unsinkable: A Memoir" detailed the highs and lows of her rocky personal life and a career which was still going strong into her 80s as she performed her one-woman stage show.
"'Singin' in the Rain' and childbirth were the hardest things I ever had to do in my life," she wrote in an earlier autobiography entitled "Debbie."
Known at one time as the foremost collector of Hollywood memorabilia, Reynolds married singer Eddie Fisher in 1955 and had two children, Carrie and Todd. The couple divorced in 1959 after he fell for Taylor.
Taylor's "Cleopatra" headdress and Marilyn Monroe's billowing "Seven Year Itch" frock would become part of the 4,000-piece haul costumes, props and furniture, most of which Reynolds eventually auctioned for more than $25 million.
Born Mary Frances Reynolds on April 1, 1932 in El Paso, Texas, the second child of railroad carpenter Raymond Francis Reynolds and his wife Maxine, she came to the notice of Hollywood studio MGM after winning a California beauty contest at age 16.
Now synonymous with tap, Reynolds had never danced professionally, according to the Internet Movie Database, when picked to star in classic musical "Singin' in the Rain."
Several more MGM musicals followed, with Reynolds typically cast as a wholesome young heroine, before she turned to more serious screen acting, as well as a career on Broadway.
Married three times, Reynolds once said she had more luck selecting restaurants than men.
First, she had to overcome the humiliation of losing Fisher to Taylor, although the two women remained close until Taylor's death in 2011.
In another turn of misfortune, Reynolds's second husband, shoe magnate Harry Karl, gambled away most of her savings.
Her third marriage to real estate developer Richard Hamlett in 1985 wasn't much more successful, ending in divorce in 1996.
To support the family, Reynolds performed at her casino in Las Vegas, where she housed her memorabilia collection until it shut in 1997.
Reynolds, admired for her versatility, starred in her own sitcom, "The Debbie Reynolds Show," in 1969-1970 and was latterly known for her Emmy-nominated role as Grace's quirky mother on NBC's "Will & Grace."
Her career in cinema was largely over by the 1970s, though she continued to star in TV movies and series. She also made regular personal appearances, acting on stage and portraying Liberace's mother Frances opposite Michael Douglas in 2013's "Behind the Candelabra."
"Bright Lights: Starring Carrie Fisher and Debbie Reynolds," a documentary about her at times rocky relationship with her daughter, premiered at this year's Cannes Film Festival and is due to air on HBO in March.