Background <p>Shampoo powder is a widely used cosmetic product for daily cleansing of hair and scalp, imparting softness, luster, and manageability. Herbal shampoo powders are gaining popularity due to their perceived safety and minimal side effects compared to synthetic alternatives.</p> Objective <p>This study aimed to formulate and evaluate an anti-dandruff shampoo powder using Harsinghar (<i>Nyctanthes arbortristis</i>), also known as Parijatha, as the primary active ingredient.</p> Methodology <p>The shampoo powder was prepared using Parijata seeds, along with Kantakari, Amla, Shikakai, Kunkudu, Rose, Henna, and Brahmi. The formulation’s physicochemical properties (pH, solubility, washability, extraction values, dirt dispersion, and general powder characteristics), foaming index, zone of inhibition (against dandruff), mineral content, solid content, cleaning action, hair surface characterization (by scanning electron microscopy), skin and eye irritation (in rats), and stability were evaluated.</p> Results and Discussion <p>The formulation demonstrated anti-dandruff activity in the zone of inhibition test. It exhibited desirable physicochemical properties, including a pH of 5.46 and a foaming index of 111.1%, and provided good conditioning for various hair types (curly, straight, and wavy). The zone of inhibition against <i>Malassezia</i> was significant compared to a marketed medicated product.</p> Conclusion <p>The herbal shampoo powder showed significant anti-dandruff properties, favorable physicochemical characteristics, and promising in-vitro results.</p> Graphical Abstract: Mechanism of Action <p></p>