The article reviews the advancements in wearable optical sensors for sweat monitoring, focusing on their principles, development, advantages, and limitations. It highlights four main analytical methods used in optical skin interfaces: colorimetry, surface-enhanced Raman spectroscopy (SERS), fluorescence, and electrochemiluminescence (ECL). The review discusses the integration of these methods with flexible and stretchable materials, microfluidic techniques, and advanced data analysis tools. Challenges such as environmental impact, data readout, and signal interference are addressed, along with future prospects for improving the performance and reliability of wearable optical sweat sensors. The article emphasizes the potential of these sensors in personalized healthcare, sports, and disease diagnosis, particularly in detecting electrolytes, metabolites, nutrients, and hormones in sweat.The article reviews the advancements in wearable optical sensors for sweat monitoring, focusing on their principles, development, advantages, and limitations. It highlights four main analytical methods used in optical skin interfaces: colorimetry, surface-enhanced Raman spectroscopy (SERS), fluorescence, and electrochemiluminescence (ECL). The review discusses the integration of these methods with flexible and stretchable materials, microfluidic techniques, and advanced data analysis tools. Challenges such as environmental impact, data readout, and signal interference are addressed, along with future prospects for improving the performance and reliability of wearable optical sweat sensors. The article emphasizes the potential of these sensors in personalized healthcare, sports, and disease diagnosis, particularly in detecting electrolytes, metabolites, nutrients, and hormones in sweat.