The purpose of this study was to explore the rotational effect of scarf osteotomy with transarticular lateral release (TALR) on hallux valgus correction. From January 2016 to January 2018, 28 consecutive patients (30 feet) were included in this study. The first intermetatarsal angle (IMA), hallux valgus angle (HVA), and round-shaped lateral edge of the first metatarsal head (R sign), and sesamoid rotation angle (SRA) were recorded prior to and 3 months after the surgery. The rotation of the capital fragment of the first metatarsal was termed the capital rotation angle (CRA) and was measured intraoperatively after the completion of scarf osteotomy. The IMA, HVA, and SRA were significantly reduced from 13.9 ± 4.9°, 34.6 ± 7.4°, and 28.7 ± 9.8° to 2.4 ± 2.3°, 7.3 ± 4.7°, and 13.4 ± 8.8°, respectively (p < .01 for all). The mean CRA was 7.0 ± 3.4° and was not significantly correlated with the reduction of IMA and SRA (p >. 05 for all); nor was it significantly correlated with IMA preoperatively and postoperatively (p >. 05 for all) or the reduction of SRA and IMA (p >. 05). The R sign was positive in 40% (12/30) of the feet preoperatively compared to 13.3% (4/30) postoperatively (p < .001). Scarf osteotomy produced a supination effect on the capital fragment of the first metatarsal and supinated the sesamoids via lateral translation of the first metatarsal head. These changes may contribute to the correction of the pronation component of hallux valgus deformity.