The aim of this study was to determine the prevalence of leptin (LEP), leptin receptors (LEPR), melanocortin-4-receptor (MC4R), proopiomelanocortin (POMC), single-minded 1 (SIM1), and SH2B1 gene variations in Turkish children and adolescents, and to conduct a detailed examination of the clinical and laboratory findings of patients with variants. In this study, we included 49 children and adolescents (29 male/20 female) who presented to the Pediatric Endocrinology clinic of Erzurum Regional Training and Research Hospital between 2017 and 2020 with obesity. Family history with regards to obesity, parental consanguinity, obesity-related comorbidities, anthropometric measurements, and laboratory tests of the patients were recorded in the clinical evaluation. LEP, LEPR, MC4R, POMC, SIM1, and SH2B1 genes, which are associated with monogenic obesity, were evaluated by the next generation sequencing analysis in all patients. The mean age of 49 patients included in the study was 8.4 ± 5.2 years (range: 0.6–16.8), their mean height standard deviation score (SDS) was 0.9 ± 1.6, mean body mass index (BMI) was 31.3 ± 8.1 kg/m2, and their mean BMI SDS was 3.5 ± 0.6. A total of four different variants (c.380C>T and c.870delG variants in MC4R gene; c.2992A>C and c.448delA variants in LEPR gene) were detected in four patients. The determination of a molecular etiology in patients with monogenic obesity is important in view of the treatment options to be introduced in the near future (MC4R agonist) and for the family to receive appropriate genetic counseling. In this study, we evaluated the clinical and genetic findings of the patients with monogenic obesity in detail, and contributed the findings of the novel variants to the literature.