Purpose: This study aims to examine the prevalence of overweight and obesity in children with type 1 diabetes mellitus (T1DM) in Hong Kong and to evaluate the association between obesity, glycemic control, and metabolic comorbidities. Methods: A retrospective cross-sectional study was conducted from 2022–2023 at the Hong Kong Children’s Hospital, enrolling all children with T1DM. Anthropometric measurements and biochemical data were extracted from medical records, and prevalence rates of metabolic complications were compared. Results: One hundred twenty-six children (41% male, 89% Asian) with a median age of 12.8 years were included. Of these, 17.5% were either overweight or obese. There were no significant differences in hemoglobin A1c values between the normal-weight and overweight/obesity groups, though the latter group required higher total daily insulin doses. Children with overweight/obesity had higher prevalence rates of hypertension (28.6% vs. 2.9%) and dyslipidemia (90.5% vs. 71.9%). They were also more likely to have hypertension (adjusted odds ratio [aOR], 18.48; 95% confidence interval [CI], 3.42–99.94) and hypertriglyceridemia (aOR, 7.71; 95% CI, 1.66–35.76). The overweight/obese group also exhibited significantly higher alanine aminotransferase levels (median, 18 IU/L vs. 14 IU/L), non–high-density lipoprotein cholesterol (HDL-C) levels (median, 3.3 mmol/L vs. 2.9 mmol/L), and triglyceride/HDL-C ratios (median, 1.09 vs. 0.52) and lower HDL-C levels (median, 1.4 mmol/L vs. 1.6 mmol/L). Among those with dyslipidemia, only 8% were started on lipid-lowering agents, while none of those with hypertension were started on antihypertensive agents. Conclusion Despite a lower prevalence of overweight/obesity in Asian children with T1DM compared to Western populations, metabolic comorbidities occur at an exceptionally high rate. Early interventions to tackle these modifiable cardiovascular risk factors are crucial to prevent long-term complications.