Nathan Hartono

Hartono was born in Singapore on 26 July 1991 to Chinese Indonesian parents, Nathan's father, Thomas Hartono, is the managing director of PT Anandini Vimala, while his mother, Jocelyn Tjioe, is the senior vice president of Singapore-based Tung Lok group, which was founded by his grandfather. Nathan has an elder brother, Norman Hartono, and a younger sister, Nydia Hartono.

Hartono completed his primary school education at Nanyang Primary School and continued to Anglo-Chinese School (Barker Road) for his secondary education before graduating from Anglo-Chinese Junior College. In 2009, he was conscripted into the Singapore Armed Forces for national service. He subsequently studied at the Berklee College of Music majoring in Music Production & Engineering in Boston, and has taken a break from school since 2014.

Coming from an English-speaking family, Hartono struggled with learning the Chinese language in primary and secondary school, describing it as an "unclimbable mountain" in a 2017 interview. It was not until he entered junior college when he discovered his newfound interest in learning Chinese. In the same interview, he added that learning the language "could open up a lot of opportunities." After his stint at Sing! China, he could finally complete sentences in Mandarin without pausing or inserting English words. He has also spoken of how he is influenced by Frank Sinatra.