Sonam has one sister, Rhea, and a brother, Harshvardhan. Rhea made her Bollywood debut as a producer with Aisha and she frequently acts as Sonam's stylist. Sonam's cousins include Boney Kapoor's son and daughter with first wife Mona - actor Arjun and Anshula - and his daughters with Sridevi - Jhanvi and Khushi.
Sonam went to Arya Vidya Mandir school in Juhu and then to the United World College of South East Asia for her International Baccalaureate. Then she studied Political Science and Economics at University of East London.