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The 'Price Tag' singer walks away with a staggering four gongs, and there are also wins for Dappy, Adele and Tinie Tempah.
Following her triumphant opening performance of the show with hit 'Do It Like A Dude' Jessie went on to win four out of five of the categories she was nominated for - Best UK Act as voted for by Capital FM listeners, Best Album, Best Newcomer and Best Song.
Earlier in the evening Jessie J told Capital she she was secretly hoping to take home at least one award in order to honour her "amazing" fans.
Other winners included Tinie Tempah, who took home the award for Best Hip Hop/Grime, Adele for 'Best R&B/Soul Act' and Rihanna, who beat Beyonce and Bruno Mars to take home Best International Act.
The award for Best Video went to Tinchy Stryder and Dappy for 'Spaceship'.
See pictures from the MOBO Awards here.