The Shake It Out band will perform at a church in east London on 26 February (16), two days after the London prizegiving, and Bloc Party will kick off the Passport to BRITs Week fundraising initiative on 15 February (16) at Bush Hall in west London.
Fans must donate $6.75 (£4.50) to gain entry into a ballot for tickets, and funds raised will go towards the War Child charity, which helps youngsters in areas of conflict.
Florence Welch writes on Twitter.com, "Pleased to announce an intimate gig for @WarChildUK on 26th Feb at @StJohnatHackney."
Frank Turner, Jamie XX and Professor Green are also taking part in the concert series.
The 2016 BRIT Awards will be held at London's 02 Arena on 24 February (16).