Wearable UV sensors are increasingly valuable for monitoring solar exposure and preventing harmful effects of UV-B radiation, such as DNA damage, skin cancer, and immune suppression. However, many current sensors require electronic components to detect UV-B radiation specifically. In this study, we developed a simple, cost-effective UV sensor using silver-ion-loaded short-chain glucan microbeads (Ag@SMB) to selectively monitor UV-B levels in sunlight. The sensor’s UV-induced colorimetric response is triggered by the reduction of Ag nanoparticles on the microbead surface, resulting in a visible color change that corresponds to accumulated UV exposure. This change can be quantified by converting the color shift into greyscale (ΔG) values. When integrated into a paper membrane, the Ag@SMB sensor maintained its UV-dose-dependent response, with ΔG values strongly correlating with UV doses measured electrically, allowing real-time measurement of UV doses ranging from as low as 28 J/m 2 to as high as 3650 J/m 2. We further developed a wearable UV sensor, such as a bracelet, by embedding Ag@SMB in an alginate film, enabling real-time monitoring of UV doses within the Minimal Erythemal Dose range for all skin types. Additionally, the Ag@SMB sensor exhibits antimicrobial properties and low cytotoxicity, making it a safe and practical tool for daily use.