The 41st edition of the music awards show was due to take place in February, as usual, at London's O2 Arena.
But uncertainty around the ongoing Covid-19 pandemic has prompted the music industry to delay it.
Organisers said they want "outstanding production levels, superstar performances and live excitement".
Geoff Taylor, chief executive of The Brits and industry body the BPI, said: "We believe that the best way to achieve this in 2021 is to move the show back a few months to May.
"We are already at work planning a spectacular event that will remind us how important music has been in getting us all through these difficult times."
The eligibility period for the awards will be altered, although music releases have continued during the pandemic.
Last year's ceremony featured performances from pop stars including Billie Eilish, Dave, Lewis Capaldi and Lizzo.