Her victory follows tours with global stars Ed Sheeran and Lewis Capaldi, and she expressed shock and gratitude for the prestigious award.
The south London-born artist has already achieved a UK number five single with 'Family Matters' and her EP SE9 – PT1 reached number 18 on the UK albums chart.
The Sound Of competition, previously won by artists like Adele and The Last Dinner Party, is voted for by a panel of over 170 industry experts and artists, including Sir Elton John and Dua Lipa.