Deep margin elevation (DME) is a minimally invasive restorative technique that relocates subgingival margins coronally to facilitate adhesive bonding and isolation. It is proposed as a conservative alternative to surgical crown lengthening for teeth with deep cervical margins. The present systematic review evaluated the restorative success and periodontal response of DME, with emphasis on long-term restoration survival, marginal adaptation, and periodontal health. Electronic searches of PubMed, Scopus, Web of Science, Embase, and CENTRAL were conducted from database inception to August 2025. Randomized controlled trials (RCTs), non-randomized clinical trials, controlled clinical trials, and retrospective studies reporting restorative or periodontal outcomes after DME were included. Eight clinical studies (n = 678) were included: two RCTs, three non-randomized clinical trials, two retrospective cohorts, and one controlled clinical trial. Follow-up ranged from three months to 12 years. Restoration survival was consistently high, with long-term success rates of 94%-100% and slightly higher survival for ceramic than for composite restorations. Pocket depth remained within healthy limits (1.9 to 2.8 mm) across all studies. Early increases in bleeding on probing (up to 53% at 12 months) and plaque index were observed, but stabilized or decreased over time with adequate hygiene. Clinical attachment loss remained stable or showed slight improvement in long-term follow-up. DME yields excellent long-term restorative outcomes and maintains periodontal health when performed with meticulous adhesive technique and appropriate maintenance. Findings of the present systematic review support its use as a conservative alternative to surgical crown lengthening.