This open-label, single-arm, interventional study titled “Evaluation of Improvement in Skin Lightening Index with Regular Sunscreen Use” aims to assess the effect of daily application of a mineral-based sunscreen (Safescreen Go) on the skin lightening index over a four-week period in individuals who had not used sunscreen in the preceding four weeks. Phototanning and uneven skin tone result from cumulative ultraviolet (UV) and visible light exposure, which stimulate melanogenesis and oxidative stress. Regular sunscreen use mitigates these effects, but compliance is often poor due to cosmetic concerns. Mineral sunscreens containing non-nano zinc oxide and iron oxides offer broad-spectrum protection against both UV and visible light and are safer alternatives to conventional chemical filters. In this study, 30 participants aged 18–60 years will apply Safescreen Go daily on the face for four weeks, with reapplication after outdoor activity. No other brightening or sunscreen products will be permitted. Assessments will be performed at baseline and after four weeks, including clinical photography, Reveal® imaging, and objective colorimetric evaluation using the Dermalab Combo device to measure melanin, erythema, and lightening indices. Participant-reported outcomes on perceived lightening and satisfaction, as well as safety evaluations for irritation or breakout, will also be recorded. The primary objective is to determine the improvement in the Lightening Index after four weeks of regular sunscreen use, while secondary objectives include assessing user satisfaction and tolerability. Data will be analyzed using descriptive statistics and paired t-tests, with significance set at p < 0.05. The study will exclude individuals with known allergies to sunscreen ingredients, those using depigmenting agents, or those with active dermatological conditions, as well as pregnant or lactating women. All participants will provide written informed consent, and Institutional Ethics Committee approval will be obtained before initiation. Confidentiality will be maintained through coded data storage. Adverse events will be documented and addressed promptly, with serious events reported to the Ethics Committee.