•Enhance transdermal drug delivery was achieved via microneedle administration.•Light responsive microneedles were designed upon iron (III) to iron (II) shift.•Long-term curative effect reduced annoying repeated administration.•The ICAMP system was comparable to lotion or cream for xerosis treatment. Dry skin, known as the xerosis, would induce deep cracks and fissures, leading to bleeding and increased risk of allergens and pathogens penetrating the skin, which may trigger allergic and irritant contact dermatitis as well as the severe infection. High-frequent administration of traditional emulsion or moisturizer often results in significantly reduced patient compliance/adherence and limited therapeutic efficacy. Microneedle (MN) patches have been extensively investigated due to their deep penetration through the epidermis for sustained release in a patient-friendly manner. In this study, an iron (III) cross-linked alginate microneedle patch (ICAMP) has been developed for long-term treatment of xerosis by delivering the ammonium lactate for local management. In order to achieve on-demand treatment, the microneedles were cross-linked with iron (III) which could be photodegraded into iron (II) by exposure to light at 405 nm, triggering microneedles to dissolve in the interstitial fluid for payload release. In such a way, the drug could be released in a well-tunable fashion by using a light-based controller, suggesting a regulated manner to treat xerosis especially under intense light radiation.