Styles earned the rare clean sweep at the 2023 ceremony held at London's O2 Arena - earning all four of awards he was up for.
Starting his wins with best pop/R&B act, Styles later won artist of the year, single of the year for 'As It Was' and album of the year for Harry's House.
During his artist of the year speech, Styles took a moment to 'acknowledge his privilege' in a nod to the controversy surrounding the award.
Artist of the year was introduced two years ago, scrapping the previous 'best male artist' and 'best female artist' gongs, in a bed for the show to be more inclusive for non-binary stars.
However, this seemingly backfired in this year's nominations when only men were nominated.
Speaking on stage, Styles – who has previous won Brits both as a solo artist and as part of One Direction – took a moment to note the women who could have had a place in the category shortlist.
"I’m very aware of my privilege up here tonight," he told the audience, before shouting out Rina Sawayama, Charli XCX, Florence + The Machine, Mabel, and Becky Hill.
During the speech, Harry also praised his family and also band One Direction, who went on an indefinite hiatus in 2018 shortly after bandmate Zayn Malik quit the group.
All the members – completed by Louis Tomlinson, Niall Horan and Liam Payne – have gone on to solo careers.
"I want to thank my family for being the most supportive, understanding, patient family," he said. "I want to thank my mum for signing me up for the X Factor without asking me."
"I also wanna thank Niall, Louis, Liam and Zayn," he added. "I wouldn’t be here without them."
Styles opened this year's Brit awards with a performance of 'As It Was', which later won single of the year.
Other big winners at this years ceremony was Beyoncé - who took home best international artist and best international song – and Wet Leg, who were awarded best new artist and group of the year.
Read more: The Brit Awards' most controversial moments
However, the ceremony was not without its hiccups – with several technical difficulties and slip-ups plaguing the show's live airing on ITV1 and ITVX.
Host Mo Gilligan made an error by accidentally calling Lewis Capaldi "Sam Capaldi" while introducing his performance of song 'Forget Me', with other artists and presenters seemingly drunk and stumbling on their words.
Tom Grennan also caused controversy by commenting on Ellie Goulding's breasts live on stage.
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