The traditional scarf osteotomy (TSO) has limited ability to correct the first metatarsal pronation. A novel modification that we refer to as a "dovetailed notch scarf osteotomy" (DNSO) has been developed to enhance the ability to correct coronal plane pronation. The study aimed to observe and compare TSO to DNSO in the treatment of moderate to severe hallux valgus deformity.This retrospective study included 78 feet that had a TSO and 105 feet that had a DNSO. Minimum follow-up was 24 months. Weightbearing computed tomography (WBCT) and weightbearing anterior-posterior (AP) radiographs were taken preoperatively and at the last follow-up. We measured the intermetatarsal angle (IMA), hallux valgus angle, distal metatarsal articular surface angle on AP radiographs and first metatarsal coronal pronation angle (α angle), tibial sesamoid coronal grading, and first metatarsal length on WBCT. Clinical assessment was done using visual analog scale (VAS), American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale, Foot and Ankle Ability Measure (FAAM), and the 36-Item Short Form Health Survey (SF-36). The occurrence of postoperative complications was also documented.The DNSO group exhibited a significantly higher correction amount of α angle and IMA (14.3 ± 9.9 and 10.3 ± 4.6 degrees) than the TSO group (8.6 ± 5.9 and 5.4 ± 5.9 degrees) during the final follow-up assessment (P < .05).The DNSO group (10.1 [8.0-12.0] degrees and 4.8 [3.9-5.6] degrees) demonstrated significantly smaller α angle and IMA compared with the TSO group (4.8 [3.9-5.6] degrees and 9.5 [7.5-11.5] degrees) at 24 months postsurgery (P < .05). The postoperative FAAM activities of daily living and SF-36 physical functioning scores were significantly higher in the DNSO group (97.2 ± 3.3 and 95.7 ± 4.4 points) compared with the TSO group (92.3 ± 3.3 and 87.7 ± 8.7 points) (P < .05). Additionally, hallux varus occurred in 1 case in the DNSO group, whereas 4 cases were observed in the TSO group.Two osteotomy methods can effectively correct moderate to severe hallux valgus deformity. Compared with the TSO, the DNSO has stronger correction ability. The most crucial aspect lies in its controllability when correcting first metatarsal pronation and addressing IMA.Level III, retrospective comparative study.