The actress, who was accompanied to the ceremony by her parents, also thanked her co-stars, crew and team for their support before wishing her fellow nominee, ‘Amour’ star Emmanuelle Riva a happy 86th birthday.
Picking up the Oscar, she said: "You guys are just standing up because I fell, and it's so embarrassing...".
22-year-old Lawrence beat Jessica Chastain for ‘Zero Dark Thirty’, Quvenzhané Wallis for ‘Beasts Of The Southern Wild’, Emanuelle Riva for ‘Amour’, and Naomi Watts for ‘The Impossible’.
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‘The Artist’ star Jean Dujardin presented her with the prize.
Before the ceremony the actress revealed she had a very stressful day ahead of the event and admitted she couldn't wait to get to an after party so she could eat.
She said: "Today was so stressful. There was everybody in, my family got ready at my house. I felt like Steve Martin in 'Father Of The Bride' with all the furniture being moved around my house. I had no time to eat. I'm starving.”