Background: Mental health and its related illness are growing concerns over the world. The early onset of emotional and behavioural problems in young children has related to a variety of health and behaviour problems in adolescence and later life as well. Mental health disorders are the leading cause of morbidity among young people worldwide, accounting for 12% of global psychiatric morbidity and 40% of DALY due to mental health disorders. A variety of psychiatric manifestations are seen in children and adolescents below the age of 17 years. This study aims to find out the prevalence of psychiatric disorders in children and adolescents attending psychiatry outpatient department in a tertiary hospital. Methods: A descriptive cross-sectional study was done from 1st October 2022 to 31st January 2023 at Child and Adolescent Psychiatry OPD of SMS Medical College. Proper written informed consent was taken before the start the of study. The intelligence quotient (IQ) was assessed by a clinical psychologist as and when required. A semi-structured proforma was used for the socio-demographic profile of patients and the International Classification of Diseases-10 (ICD-10) was used to make the diagnosis. Results: A total of 340 participants were analysed during the study period and this study comprised 194 males and 146 females. Most of the children belonged to the age group of 11-15 years (46.48%) followed by the ages of 6-10(27.94%). Most of the children belonged to Rural backgrounds (56%). The most common diagnosis made was Mental Retardation (36.48%), Hyperkinetic disorders (19.12%), Pervasive Developmental Disorders (11.47%), and Dissociative (Conversion) Disorders (6.48%). Conclusion: The psychiatric illnesses were found higher in the 11-15 years of age group with male preponderance. Most of the adolescents were from rural areas. Mental retardation and Hyperkinetic disorders were the most common psychiatric disorders reported. Psychiatric disorders are pervasive and troublesome in children and adolescents. Our study supports the findings of other studies in predicting patterns of psychiatric disorders that would help in applying suitable screening procedures and the importance of identification and subsequent management of psychiatric conditions.