Introduction: Extensive ossification over the semicircular canal is not common in the surgery of otitis media. This study aimed to reduce intraoperative and postoperative complications among patients with extensive ossification over the lateral semicircular canal and concomitant otitis media. Methods: The patients’ clinical data were retrospectively reviewed to determine the preoperative imaging characteristics of perilabyrinthine ossificans and key points of surgical operation. The data of 156 patients who underwent radical mastoidectomy or tympanoplasty between January 2016 and December 2018 due to chronic otitis media or cholesteatoma were reviewed. Seven patients with extensive ossification over the lateral semicircular canal were identified, and their preoperative imaging results, intraoperative procedures, and postoperative symptoms were evaluated. Results: The incidence of extensive ossification over the lateral semicircular canal among patients with chronic otitis media was 4.5% (7/156). Ossification occurred in the periphery of the lateral semicircular canal; the osseous tissue frequently fused with the osseous lateral semicircular canal, obscuring the boundaries between the two structures. A semicircular canal fistula was observed in two of the seven patients with extensive ossification over the lateral semicircular canal. The two patients underwent surgical patching or filling and symptomatic hormone treatment. Postoperative vertigo occurred in both patients and subsided within 1–3 months. There was no significant difference between preoperative and postoperative hearing thresholds. Conclusion: Extensive ossification over the lateral semicircular canal has a low incidence and may be discovered through preoperative imaging evaluation, enabling medical personnel to engage in adequate preoperative preparations. During the surgical procedure, navigational landmarks are required to determine the anatomical structures. The management of semicircular canal fistulas is essential to the reduction of intraoperative and postoperative complications.