The use of recirculating light confined within a microcavity to sensitively measure the surrounding environment is a highly promising technology. The wide attention that the whispering gallery mode (WGM) platform has attracted is driven by its versatility and extreme sensitivity. Their unique property of confining photons for a long time in small volumes enables precision measurements for various applications in sensing. In comparison with other materials, polymer-based resonators hold technological promise for constructing low-cost WGM sensing devices with ease of fabrication and flexibility. Organic dye-doped polymers have been widely used as gain media in optical amplifiers and solid-state dye-lasers due to their wide range of tunability. With the headways in microfabrication, polymer-based resonator devices can be configured for a wide variety of physical, chemical or biomolecular sensing applications. This talk gives a brief description of WGM optical microcavities followed by discussions including different geometries, choices of material systems, and new approaches to sensor operation. Recent important developments are highlighted, including advancements in polymer cylindrical WGM microlasers and their applications as optical sensors. Many of the sensing mechanisms implemented on polymer optical fiber-based devices are discussed in terms of their potential for easy implementation, more sensitive and rapid analysis