The 28-year-old triumphed for the first time at Oscars defeating strong contenders like Isabelle Huppert (Elle), Ruth Negga (Loving), Natalie Portman (Jackie) and veteran actress Meryl Streep (Florence Foster Jenkins).
Stone's performance, as an aspiring actress working as a barista in a cafe, in the film was praised for being superbly smart, witty and vulnerable. Her half-spoken, half-sung monologue - "Audition (The Fools Who Dream)"- was one of the most poignant moments from the movie.
An emotional Stone thanked fellow nominees Meryl Streep and Ruth Negga and her family.
"Moments like this is a huge confluence of luck and opportunity. I want to thank Damien Chazelle for giving me the opportunity to be part of the project that was so special and once in a lifetime. I am so grateful to be involved in this film and thank you for your patience.
Ryan Gosling thank you for making me laugh and for being the greatest partner in this crazy adventure... I still have a lot of growing and working to do and this guy (Oscar) is a symbol of continuing on that journey, and I am so grateful for that," she said.
This year, the actress had won almost all the trophies-- Golden Globe, Bafta and Screen Actors Guild Award, in the run-up to the Oscars.
"La La Land," the joyous musical about a pair of star- crossed creatives (Stone, Ryan Gosling) struggling to connect with each other and their respective careers in the entertainment industry had received a historic 14 Oscar nominations.
Stone was previously nominated for best-supporting actress for the role of a recovering drug addict and the daughter of Michael Keaton's title character in 2014's "Birdman."
Born in in Scottsdale, Arizona, Stone began acting as a child as a member of the Valley Youth Theatre in Phoenix. She had her TV breakthrough after winning the part of Laurie Partridge in the VH1 talent/reality show "In Search of the Partridge Family".
Stone made her feature film debut as Jules in "Superbad" (2007) and, after a string of successful performances, her leading role in 2010 film "Olive in Easy A" established her as one of the most sought after young talents.
Other than her Oscar nominated characters, Stone has earned praises for her performance in films like "The House Bunny," "Magic in the Moonlight," independent comedy-drama "Paper Man", "The Help" and "Crazy Stupid Love".