The Custom Skincare Serum segmentation by application is anchored in three primary consumer intents: anti‑aging, brightening, and sensitive‑skin care. Anti‑aging serums, which incorporate retinoids, peptides, and antioxidants, dominate the market, accounting for roughly 45 % of total revenue due to high willingness to pay for clinically validated wrinkle‑reduction outcomes. Brightening formulations, typically based on vitamin C, niacinamide, or licorice root extracts, capture about 30 % of the market; their growth is propelled by demand for hyperpigmentation correction across diverse skin tones. Sensitive‑skin serums, formulated with minimal irritants, hypoallergenic bases, and soothing agents such as centella asiatica, represent the remaining 25 %, reflecting a rising segment of consumers with barrier‑compromised skin who prioritize safety over aggressive efficacy. Collectively, these application categories delineate the market’s revenue distribution and guide product‑development pipelines, as each segment’s proportion directly influences the allocation of R&D and marketing resources within the overall Custom Skincare Serum market.