Festival dijadwalkan dari 23 Sep hingga 26 Sep 2021 (3 hari).
Firefly Music Festival berlangsung di Dover, United Kingdom. Berikut adalah alamat lengkap festival: The Woodlands of Dover International Speedway, Dover
Billie Eilish, The Killers, Tame Impala, Machine Gun Kelly, Lizzo, Girl In Red, Tate McRae, Glass Animals, Wiz Khalifa, Oliver Tree.
Genre dan sub-genre yang paling populer dari edisi sebelumnya adalah:
electronic
hip hop
rock
indie
indie rock
alternative
electronica
electro
alternative rock
house
dance
experimental
indie pop
ambient
downtempo
psychedelic rock
trap
deep house
dubstep