Wearable antennas play a critical role in the continuous health monitoring capabilities of Wireless Body Area Networks (WBANs), necessitating compact, conformal designs that ensure both high performance and user safety. However, many existing designs suffer from bulky form factors, limited dual-band functionality, and elevated Specific Absorption Rate (SAR) levels. In this work, a conformal, dual-band circular-ring slot antenna is proposed, fabricated on a flexible denim substrate characterized by a relative permittivity of ε_r = 1.6, a loss tangent of tan δ = 0.002, and a thickness of 0.7 mm. The antenna operates within the 2.45 GHz and 5.85 GHz ISM bands, employing a simple microstrip feed and a partial ground plane to achieve realized gains of 6.1 dB and 7.2 dB, along with return loss minima of –31 dB and –26 dB, respectively. Experimental measurements and full-wave electromagnetic simulations demonstrate consistent impedance characteristics, uniform gain performance, and SAR values of 0.197 W kg⁻¹ and 0.6413 W kg⁻¹ well below the FCC safety threshold of 1.6 W/kg. Furthermore, conformal bending tests over radii ranging from 50 mm to 70 mm reveal negligible degradation in antenna performance, underscoring its mechanical robustness under realistic wearable conditions. The antenna’s ultra-thin profile, low SAR, and efficient dual-band operation position it as a promising candidate for integration into compact, safe, and scalable wearable devices targeting healthcare and Internet of Things (IoT) applications.