Objectives <p>To compare fascia lata allograft (FLA) and subepithelial connective tissue graft (SCTG) for peri-implant mucosal augmentation performed simultaneously with implant placement.</p> Materials and methods <p>This prospective, randomized, examiner-blinded pilot clinical trial enrolled 16 patients requiring single-tooth implant placement with a thin peri-implant soft-tissue phenotype. Participants were randomly allocated (1:1) to SCTG or FLA. The primary outcome was peri-implant mucosal thickness (PMT) measured by using a customized stent-guided transmucosal method at standardized buccal reference points. Secondary outcomes included keratinized mucosal width (KMW), postoperative pain (VAS), and modified wound healing index (MWHI). Follow-up was 24 weeks.</p> Results <p>Both groups demonstrated significant improvements in PMT and KMW over time. Between-group differences were generally non-significant, except localized PMT differences at the intermediate reference level, favoring SCTG at later visits. FLA showed lower postoperative pain at selected time points. Healing outcomes were comparable.</p> Conclusion <p>Both SCTG and FLA were effective for peri-implant mucosal augmentation. FLA may represent a viable alternative that avoids donor-site morbidity. Larger long-term trials are required.</p> Clinical relevance <p>FLA can be considered a viable alternative for enhancing peri-implant mucosal thickness around simultaneously placed dental implants.</p> Trial registration <p>ClinicalTrials.gov NCT04679922, registered on December 22, 2020, and retrospectively registered.</p> Graphical Abstract <p></p>