Robin William Askin was born in Sydney, New South Wales on 4 April 1907, at the Crown Street Women's Hospital, the eldest of three sons of Ellen Laura Halliday (née Rowe) and William James Askin, an Adelaide-born sailor and worker for New South Wales Railways. His parents later married on 29 September 1916. Askin spent his early years in Stuart Town before his family moved to Glebe, a working-class inner-city suburb of Sydney. After primary education at Glebe Public School, Askin was awarded a bursary to study at Sydney Technical High School, where he sat in the same class as the future aviator Charles Kingsford Smith. At school he gained good marks, with a particular interest in Mathematics and History, and enjoyed swimming and Rugby League. He completed his Intermediate Certificate in 1921.