Background/Objectives In recent years, there is a growing incidence of granulomatous lobular mastitis (GLM), but studies about the coexistence of erythema nodosum (EN) and GLM are rare. In this study, we assess the clinical characteristics and predictive factors of EN in GLM. Methods A total of 303 patients diagnosed with GLM were enrolled from January 2012 to October 2018 at the second affiliated Hospital of Guangzhou University of Traditional Chinese Medicine, including 78 patients with EN. Follow-up data included: lesion site, lesion size, therapy approaches, course of GLM, course of EN, the recurrence of disease, possible causes. All patients had pathologic confirmation of GLM based on core needle biopsy (CNB) or surgical excision. Result Fever in the EN group was significantly more common compared to the non-EN group (44.87% vs 12.89%, P < 0.001). The proportion of lesion range >2 quadrants in the EN group was significantly higher than that in the non-EN group (42.31% vs 16.00%, P < 0.001). The course of the disease was longer in the EN group compared to the non-EN group (10.32 moths vs 8.74 moths, P < 0.001). Patients with EN had a trend towards a higher risk of recurrence (5.13% vs 1.33%, P = 0.055). Conclusion EN is more likely to be found in GLM patients with breast lesion range >2 quadrants. The presence of EN in GLM indicates that the condition becomes more severe and the course of GLM also becomes longer.