Introduction: Oral immunotherapy (OIT) has been reported to be effective but associated with a risk of severe symptoms. Thus, an OIT method with decreased risk is required. Objectives: We aimed to evaluate the efficacy and safety of low- and high-dose OIT regimens in children with severe milk allergy. Methods: Overall, 33 participants (median age, 9 years; median final dose of the milk oral food challenge [OFC], 2 mL) were included. The participants were randomly assigned to groups that received either a low (20 mL; n = 19) or high (100 mL; n = 14) maintenance target dose of OIT. The dose was gradually increased to the target dose in the rush escalation phase and was then maintained daily at home. The primary endpoint was the final OFC dose at 6 months of OIT. Adverse events during OIT were evaluated. Results: The final OFC dose after OIT was significantly higher than that before OIT in both groups (low-dose, p = 0.000; high-dose, p = 0.006), but there was no significant difference in the final OFC dose between the 2 groups (p = 0.767). In the maintenance phase, the high-dose group had significantly more severe symptoms than did the low-dose group (0.5%, 11/2,355 total intake events vs. 0.1%, 4/3,230 total intake events; p = 0.018). Conclusions: An equally increased dose effect was observed for maintenance OIT doses of 20 and 100 mL in children with severe milk allergy. The risk of severe symptoms in the maintenance phase was lower in the low-dose group. A low-dose OIT regimen is recommended for severe milk allergy.