This video article demonstrates internal ptosis repair using Müller’s muscle resection. The video outlines key steps including lid eversion, identification and resection of Müller’s muscle, and conjunctival closure. A preoperative phenylephrine test assesses Müller’s muscle responsiveness and predicts surgical success; a positive response—eyelid elevation after topical application—supports proceeding with this posterior approach. Intraoperatively, the muscle is isolated by everting the upper eyelid and dissecting it from surrounding tissue before resecting a segment based on preoperative assessment. The case highlights decision-making based on lid anatomy and patient response, offering a concise visual guide to this technique.