Baynes was born in 1986 to parents Marton and Barbara in Gisborne, New Zealand. He's the youngest of three children, and his older brother Callum introduced him to basketball. Baynes' family moved from Gisborne to Mareeba, Australia, when he was three years old. His athletic career started with rugby at Mareeba State High School, and he eventually quit rugby in favor of focusing on basketball full-time. After high school, Baynes attended the Australian Institute of Sport for one year before heading to the United States to attend Washington State. He owns a Bachelor of Science in kinesiology. Baynes likes to spend his free time working with veterans or at youth basketball clinics. You can follow Baynes on Twitter (@aronbaynes) and Instagram (@houseobayne).