Aim: The study aimed to longitudinally evaluate the efficacy of gingival unit grafts (GUGs), a modification of free gingival grafts, in the management of Miller's class I and class II recession defects in mandibular anterior region, over a period of 18 months. Materials and methods: 17 subjects with 21 recession defects in mandibular anterior region were treated using GUG. Clinical parameters of recession depth (RD), clinical attachment levels (CALs), and keratinized tissue width (KTW) were recorded at baseline, 1, 6, and 18 months. Patient-centered outcomes were measured using a visual analog scale (VAS) for pain and discomfort on 14th postoperative day and for treatment satisfaction at the end of 18 months. Results: There was a statistically significant improvement in RD, CAL, and KTW at 18 months when compared to baseline levels. A mean root coverage (MRC) percentage of 84.76 ± 11.79% was achieved at the end of 18 months. Patient-related outcomes for VAS for pain and discomfort as well as treatment satisfaction showed favorable results. Conclusion: GUG can be used as a predictable treatment modality for Miller's class I and class II recession defects in mandibular anterior region. The results obtained can be well maintained over 18-month period with optimal maintenance care. Clinical significance: The advantage of involving marginal gingiva in GUG results in a well-contoured graft, which increases the ease of adaptation and suturing. The biological characteristic of intact marginal vasculature results in early integration of graft into the recipient area and greater success in graft survival over denuded root surface, causing better long-term RC outcomes.