The star was overcome with emotion after out fellow nominees Meryl cocktail dresses , Ruth Negga, Natalie Portman, and Isabelle Huppert for the gong.


The actress began her acceptance speech by praising her fellow nominees and thanking her family.


She went on: 'I realise a moment like this is a huge confluence of luck and opportunity and so I want to thank Damien Chazelle for the opportunity to be part of a project that was so special and once in a lifetime.' 


'I'm so grateful to have been involved in this film and thank you for your faith and your patience and such a wonderful experience, and Ryan Gosling, thank you for making me laugh and for always raising the bar and for being the greatest partner on this crazy adventure. ' 


Emma concluded: 'I still have a lot of growing and learning and work to do and this guy is a really beautiful symbol to continue on that journey. And I'm so grateful for that.'


La La Land also won the awards for cinematography, directing, original score, original song, and production design. 


Damien Chazelle won the Oscar for directing, while the film's song City Of Stars was the winner of Original Song. She had earlier dazzled in a beaded golden Givenchy dress while accepting the Best Actress Oscar for her role in La la Land. 


But Emma Stone swapped the elaborate gown for something more comfortable as she stepped out at the Vanity Fair party dressed in a black blazer adorned with white spots. 


Sporting a white satin mini dress teamed with black strappy heels, the star also wore her red hair in an updo after appearing in loose tousled curls at the Dolby Theatre ceremony.


She also pinned a blue ACLU ribbon to her blazer - joining the likes of Ruth Negga and Karlie Kloss who also fixed them to their gowns.


The ribbons serve as a symbol of solidarity for the American Civil Liberties Union. 


Emma looked in good spirits after her big win, having earlier accepted the Best Exquisite Light Mint LF19927 Pearls Side Cutout Prom Gown Oscar in a tearful acceptance speech. 


Ryan Gosling had been nominated for best actor but lost out to Casey Affleck who won for Manchester By The Sea. 


Casey appeared genuinely surprised and somewhat overcome by his win. 


After taking the stage to receive his Oscar from Brie Larsen, he paused with his hand over his mouth.


'This means so much to me. Dammit,' he began.


He then praised fellow nominee Denzel.


'One of the first people who taught me how to act was Denzel Washington and I just met him tonight,' he said. 'Thank you.'


Casey continued: 'Man, I wish I had something bigger and more meaningful to say, but I'm just glad to be a part of this community. I'm dumbfounded to be included.'


After thanking his co-stars and director Kenneth Lonergan, he gave a shout out to Matt Damon who was one of the producers of Manchester By The Sea and who had handed Casey the lead role after having to drop out due to a scheduling conflict.


He then finished with a message to his brother: 'Ben, I love you. You ain't heavy.' 


Viola Davis won her first Academy Award for Fences.


The three-time nominee picked up best supporting actress and delivered a long and rambling speech.


Viola, 51, broke down in tears as she opened her speech and went on to say: 'We are the only profession to celebrate what it means to live a life.'


She also thanked her co-star and director: 'And captain, my captain Denzel Washington. Thank you for putting two entities in the driving seat: August and God. and they served you well.'


Mahershala Ali won the first award of the night - best supporting actor for Moonlight, that went on to win Best Picture. 


The 43-year-old had gained critical acclaim for his role as a drug dealer named Juan, in the drama and he beat out nominees Jeff Bridges, Lucas Hedges, Dev Patel, and Michael Shannon.


It capped a great week for the actor who welcomed his plus size dresses child, a daughter, with his wife Amatus Sami-Karim four days ago. 


In an emotional acceptance speech, he thanked his 'wonderful teachers and professors' as well as his director Barry Jenkins.


'It's not about you, it's about these characters. You are a servant. You're in service to these stories,' he said.