In the past five years, significant progress has been made in preparation of various molecularly imprinted polymer (MIP)-based materials for applications in bioassays and biotransformation. This chapter reviews the important advances in these two fields. The first part mainly focuses on the development of various MIP-based bioassays that convert the rebinding of template to the imprinted cavities into measurable luminescent signals, including fluorescence, phosphorescence, Raman scattering, diffraction, and the like. In addition, MIP-based bioassays that are measured by surface plasmon resonance or quartz crystal microbalance are also discussed. In the following part, representative biotransformation reactions that make use of MIPs are summarized. In the last part of this chapter, some remaining challenges are briefly discussed for further development of the two fields.