Valorization of Phoenix dactylifera L. (date) seeds, an abundant agro-industrial byproduct, offer a sustainable approach to developing multifunctional ingredients for dermocosmetic photoprotection. Rich in polyphenols, flavonoids, and lipophilic antioxidants, date seed extracts and oils demonstrate promising UV-absorbing, anti-inflammatory, and free-radical-scavenging properties. Recent in vitro, ex vivo, and preclinical studies underscore their potential as bioactive agents in sunscreen formulations, supporting both skin barrier integrity and oxidative stress mitigation, although clinical validation is still required. This review consolidates current knowledge on the phytochemical profile and biological efficacy of date seed derivatives, with emphasis on their integration into advanced delivery systems such as nanocarriers, Pickering emulsions, and cyclodextrin complexes to enhance photostability, skin permeability, and esthetic acceptability. Safety aspects, including allergenicity, phototoxicity, and regulatory gaps, are critically examined alongside environmental and ethical advantages, including biodegradability and vegan suitability. The findings advocate for the inclusion of Phoenix dactylifera L. seed actives in next-generation dermocosmetic sunscreens that align with circular bioeconomy principles, consumer demand for “reef-safe” products, and evolving international regulations. Further clinical validation is encouraged to fully translate these botanically derived agents into effective and ethically sound sun care innovations.