Background Chronic subdural hematoma (cSDH) is a common neurosurgical condition, and middle meningeal artery embolization (MMAE) has emerged as a minimally invasive adjunct to surgery, but optimal timing remains unclear. Purpose To investigate radiographic and clinical outcomes of patients with cSDH undergoing MMAE as an adjunct to surgical evacuation, focusing on order and timing of MMAE relative to surgery. Materials and Methods This multicenter, retrospective study included consecutive patients undergoing MMAE adjunct to surgery for cSDH at 10 U.S. centers from September 2018 to September 2023. Clinical and radiographic characteristics and outcomes were examined in MMAE before or after surgery. Primary outcomes included recurrence requiring reoperation and technical success of MMAE. Secondary outcomes included radiographic success, rate of change in hematoma thickness, and functional outcome. Propensity score matching (PSM) balanced baseline characteristics. χ2 and Mann-Whitney U tests were used. Results Of the 266 MMAE procedures included in the study (237 patients; median age, 73 years [IQR, 65-80 years]; 175 [73.8%] male), 85 (32.0%) were performed before surgery and 181 (68.0%) were performed after surgery. After PSM, no evidence of differences was found in reoperation (8% [four of 48] vs 4% [four of 93]; P = .90) or technical success (100% [48 of 48] vs 98% [91 of 93]; P = .31) between groups. Similarly, no evidence of differences was observed between MMAE performed within 2 days or 3-7 days after surgery in PSM analysis in reoperation (6% [three of 52] vs 8% [three of 37], respectively; P = .67) or procedural success (98% [51 of 52] vs 100% [37 of 37], respectively; P = .40). The unmatched analysis for order and timing was underpowered to detect differences in reoperation below 11.6% and 14.6%, respectively, and in technical success below 8.5% and 11.3%, respectively, and the matched analyses were more underpowered. Conclusion The cohort did not show statistically significant differences in technical success or reoperation rates based on the timing and order of MMAE relative to surgical evacuation, although larger studies are needed to confirm these observations and rule out smaller, clinically meaningful differences. © RSNA, 2025 Supplemental material is available for this article.