Background Mastocytosis is a heterogeneous group of rare disorders characterized by the accumulation of clonal mast cells in organs such as the skin and bone marrow. The diagnosis of cutaneous mastocytosis (CM) is based on clinical findings, positive Darier's sign, and histopathology, if necessary. Methods Medical records of 86 children with CM diagnosed during a 35‐year long period were reviewed. Most patients (93%) developed CM during the first year of life (median age 3 months). Clinical features at presentation and during the follow‐up period were analyzed. Baseline serum tryptase level was measured in 28 patients. Results A total of 85% of patients had maculopapular cutaneous mastocytosis/urticaria pigmentosa (MPCM/UP), 9% had mastocytoma, and 6% had diffuse cutaneous mastocytosis (DCM). Boy to girl ratio was 1.1:1. Fifty‐four of 86 patients (63%) were followed from 2 to 37 years (median 13 years). Complete resolution was registered in 14% of mastocytoma cases, 14% of MCPM/UP, and in 25% of DCM patients. After the age of 18, skin lesion persisted in 14% mastocytoma, 7% MCPM/UP, and 25% children with DCM. Atopic dermatitis was diagnosed in 9.6% of patients with MPCM/UP. Three of 28 patients had elevated serum tryptase. Prognosis in all patients was good, and there were no signs of progression to systemic mastocytosis (SM). Conclusion To the best of our knowledge, our results represent the longest single‐center follow‐up study of childhood‐onset CM. We found no complications of massive mast cell degranulation or progression to SM.