AIM: The aim of this study was to investigate the non-inferiority of alveolar ridge preservation (ARP) with membrane stabilization compared with non-stabilization, focusing on changes of soft-tissue contour in periodontally compromised extraction sockets. Secondary outcomes included changes in hard-tissue contour, patient-reported outcomes and new bone formation. MATERIALS AND METHODS: Twenty-four patients with periodontally compromised teeth were randomly assigned to ARP with (test group) or without (control group) membrane stabilization. To assess profilometric and hard-tissue dimensional changes, dental impressions and cone beam computed tomography scans were performed at baseline (T0), immediately after ARP (T1) and 4 months post surgery (T2). Soft-tissue healing in open healing sites was evaluated at T2, and wound closure was assessed 10 days post surgery. Patient-reported outcomes were documented, and core biopsies were obtained for histomorphometric analysis. RESULTS: The absolute profilometric horizontal width change at 3 mm below the crest in the test group was not inferior to that in the control group. For the relative values, horizontal width reduction (3 and 5 mm below the crest) and volumetric shrinkage (3-5 mm below the crest) were lower in the test group. No significant differences were observed in bone dimensional changes, wound healing, pain and swelling or histomorphometric outcomes. CONCLUSION: ARP with membrane stabilization in periodontally compromised extraction sockets is non-inferior in terms of soft-tissue contour changes to those without membrane fixation. TRIAL REGISTRATION: Clinical Research Information Service (CRIS), KCT0005280. Registered 4 August 2020, https://cris.nih.go.kr/cris/search/detailSearch.do?seq=19165&search_page=L.