Nicholas Caradoc Hoult was born on 7 December 1989 in Wokingham, Berkshire, to Glenis (née Brown), a piano teacher, and Roger Hoult, a commercial pilot. His middle name, Caradoc (pronounced /ka.ˈrɑː.dɔk/), is Welsh and translates to "The Beloved One". His paternal grand-aunt was Dame Anna Neagle, a stage and film actress active in the 1930s and 1940s. He has three siblings: an elder brother who is a United States–based biology student; and two sisters, both of whom are actresses. Hoult spent most of his childhood at his family's residence in Sindlesham, an estate village in the borough of Wokingham. His older siblings were interested in acting and dancing from an early age, taking classes and attending auditions. As a child, he began accompanying them and developed his own interest in acting. He discussed his childhood and his relationship with his siblings in a 2011 interview with The Guardian saying, "[we were] pretty outdoorsy normal kids running around in the garden and making tree houses ... it was very normal".
During Hoult's childhood, his father was regularly working away from home and his brother was away attending school. As a result, he spent most of his time with his mother and sisters; he said being raised by women might have helped him "steer clear of some pitfalls that guys who didn't grow up with women would fall into". Hoult was educated at The Coombes Infant and Nursery School and then Arborfield Church of England Junior School. He practised ballet with his sisters and took part in productions of Swan Lake and The Nutcracker with the English National Ballet. Although he initially wanted to attain advanced level certificates in English, Biology, and Psychology, in 2002, aged 12, he decided instead to attend acting school at Sylvia Young Theatre School. At age 14, he left to attend the Church of England's secondary school Ranelagh School in Bracknell, Berkshire. Hoult played trombone as a child and was a member of the local choir.