Many trans and gender diverse (TGD) people have gender identities that are not exclusively male or female but instead fall in-between or outside of the gender binary (non-binary). It remains unclear if and how those with non-binary gender identity differ from TGD individuals with binary identities. We aimed to understand the sociodemographic and mental health characteristics of people with non-binary identities compared with binary TGD identities. We performed a retrospective audit of new consultations for gender dysphoria between 2011 and 2016 in three clinical settings in Melbourne, Australia; (1) Equinox Clinic, an adult primary care clinic, (2) an adult endocrine specialist clinic, and (3) the Royal Children's Hospital, a child and adolescent specialist referral clinic. Age (grouped by decade), gender identity, sociodemographic, and mental health conditions were recorded. Of 895 TGD individuals, 128 (14.3%) had a non-binary gender. Proportions differed by clinical setting; 30.4% of people attending the adult primary care clinic, 7.4% attending the adult endocrine specialist clinic, and 8.0% attending the pediatric clinic identified as non-binary. A total of 29% of people in the 21-30-year-old age-group had a non-binary gender identity, higher than all other age-groups. Compared to TGD people with a binary gender identity, non-binary people had lower rates of gender-affirming interventions, and a higher prevalence of depression, anxiety, and illicit drug use. Tailoring clinical services to be inclusive of non-binary people and strategies to support mental health are required. Further research to better understand health needs and guide evidence-based gender-affirming interventions for non-binary people are needed.