Aging lips often appear thin, inverted, and poorly defined due to disproportionate atrophy of deep labial fat and mucosa with relative preservation or increase of superficial fat. Traditional augmentation focused on superficial volumization can blur aesthetic landmarks and fail to restore eversion. The authors describe a targeted, anatomy-guided technique that deposits hyaluronic acid filler into the suborbicularis oris (deep labial) fat through an intramucosal approach at the dry–wet border to re-establish deep structural support and achieve lip eversion while preserving the vermilion breakpoints and Cupid bow. The protocol emphasizes preprocedure symmetry assessment, conservative aliquots (typically 0.5–1.0 mL per lip per session, e.p.t.q.® Lidocaine S 300, JETEMA Co., Ltd. Korea), choice of filler with balanced viscoelasticity and high cohesion for dynamic function, and plane-specific delivery using either needle for focal shaping or cannula for safer broad eversion. Practical safety measures include avoidance of commissural entry points, awareness of variable superior and inferior labial arterial courses, and staged dosing to minimize surface irregularity and overprojection. In clinical practice, this deep-plane strategy improves vermilion show, border definition, and commissure orientation with a natural feel and motion. The authors propose this approach as a reproducible method that aligns with contemporary fat-compartment aging models and may reduce complications associated with superficial overfilling.