Objective: The second consensus study on idiopathic granulomatous mastitis (IGM) aimed to establish treatment options based on the clinical classification proposed in the first consensus, standardize criteria for treatment discontinuation, and develop follow-up protocols. Method: A structured methodology, identical to the first consensus study, was employed. An 11-member working group of breast surgeons experienced in IGM from various clinics across the country was formed. The modified Delphi method was used, with a consensus threshold of 80% agreement. Results: Three voting rounds were conducted to develop the IGM treatment algorithm. In Round 1, observation was established as the first-line option for Type 1 disease (81%) and pregnancy/lactation cases (85%). Round 2 achieved consensus on systemic steroids (SS) as the first-line treatment for Type 3 cases (84%), combination therapies for resistant cases (82%), and reclassification of recurrent cases to guide treatment planning (94%). In Round 3, consensus was reached on the use of immunosuppressive therapy (IMT) for cases where steroids are contraindicated in Type 3 (81%), the use of IMT for resistant cases (93%), avoiding surgery as the first-line option for Type 1 cases (81%), and requiring complete clinical and radiological response before discontinuing treatment (81%). However, no consensus was reached on the first-line treatment for Type 2 disease. Conclusion: This consensus study successfully developed a treatment algorithm for IGM, prioritizing observation for Type 1 disease and cases involving pregnancy or lactation, and recommending systemic steroids (SS) and immunosuppressive therapies for Type 3 cases. The findings underscore the critical importance of achieving complete clinical and radiological remission before discontinuing treatment. However, the lack of consensus on the treatment of Type 2 disease highlights the need for further research into this challenging subtype.