As an emerging hybrid imaging modality, microwave-induced thermoacoustic imaging (MTAI), using microwaves as the excitation source and ultrasonic signals as the information carrier for combining the characteristics of high contrast of electromagnetic imaging and high resolution of ultrasound imaging, has shown broad prospects in biomedical and clinical applications. The imaging contrast depends on the microwave-absorption coefficient of the endogenous imaged tissue and the injected MTAI contrast agents. With systemically introduced functional nanoparticles, MTAI contrast and sensitivity can be further improved, and enables visualization of biological processes in vivo. In recent years, functional nanoparticles for MTAI have been developed to improve the performance and application range of MTAI in biomedical applications. This paper reviews the recent progress of functional nanoparticles for MTAI and their biomedical applications. The challenges and future directions of microwave thermoacoustic imaging with functional nanoparticles in the field of translational medicine are discussed.As an emerging hybrid imaging modality, microwave-induced thermoacoustic imaging (MTAI), using microwaves as the excitation source and ultrasonic signals as the information carrier for combining the characteristics of high contrast of electromagnetic imaging and high resolution of ultrasound imaging, has shown broad prospects in biomedical and clinical applications. The imaging contrast depends on the microwave-absorption coefficient of the endogenous imaged tissue and the injected MTAI contrast agents. With systemically introduced functional nanoparticles, MTAI contrast and sensitivity can be further improved, and enables visualization of biological processes in vivo. In recent years, functional nanoparticles for MTAI have been developed to improve the performance and application range of MTAI in biomedical applications. This paper reviews the recent progress of functional nanoparticles for MTAI and their biomedical applications. The challenges and future directions of microwave thermoacoustic imaging with functional nanoparticles in the field of translational medicine are discussed.