At age 11, Eilish began writing and singing her own songs, taking after her older brother Finneas O'Connell who was already writing, performing and producing his own songs with his band.
Da Eilish var 11, begyndte hun at skrive og synge sine egne sange, inspireret af sin bror Finneas O'Connell, der allerede skrev, spillede og producerede egne sange med sit band.