Thermal emission, characterized by broadband, unpolarized, and incoherent nature, is unsuitable for many infrared applications. Metasurfaces, composed of two-dimensional subwavelength artificial nanostructures, have emerged as a promising platform for controlling thermal emission due to their flexibility in tuning optical properties. Recent advancements have demonstrated the ability to tune multiple degrees of freedom in thermal emission, including wavelength, polarization, radiation angle, and coherence. This review covers recent progress in regulating thermal emission through metasurfaces and their applications in infrared sensing, radiative cooling, and thermophotovoltaic devices. Key topics include: 1. **Wavelength-Selective Thermal Emission**: Metasurfaces, such as metal-insulator-metal (MIM) structures and multi-resonant meta-atoms, have been designed to achieve narrowband and broadband thermal emission. 2. **Angular Dependence of Thermal Emission**: Mechanisms like critical coupling, plasmon-phonon coupling, and Fano resonance have been explored to control the angular response of thermal emission. 3. **Polarized Thermal Emission**: Linearly and circularly polarized thermal emission have been achieved using metasurfaces with antenna designs, grating structures, and chiral metasurfaces. 4. **Coherent Thermal Emission**: Techniques to enhance spatial and temporal coherence, such as coupling to surface-phonon polaritons (SPhPs) and surface-plasmon polaritons (SPPs), have been developed. 5. **Dynamic Tunable Thermal Emission**: Active materials like graphene and phase change materials (PCMs) have been integrated with metasurfaces to enable dynamic modulation of thermal emission properties. 6. **Nonreciprocal Thermal Emission**: Violation of Kirchhoff's law through magneto-optical materials and magnetic Weyl semimetals has been explored for advanced thermal management applications. 7. **Near-Field Thermal Emission**: Near-field thermal emission, which exceeds the blackbody limit, has been studied for enhanced heat transfer and energy harvesting. These advancements have opened new avenues for infrared applications, including passive radiative cooling, thermophotovoltaic devices, thermal camouflage, thermal imaging, and biochemical sensing. The review highlights the potential of metasurfaces in addressing the challenges of thermal management and infrared technology.Thermal emission, characterized by broadband, unpolarized, and incoherent nature, is unsuitable for many infrared applications. Metasurfaces, composed of two-dimensional subwavelength artificial nanostructures, have emerged as a promising platform for controlling thermal emission due to their flexibility in tuning optical properties. Recent advancements have demonstrated the ability to tune multiple degrees of freedom in thermal emission, including wavelength, polarization, radiation angle, and coherence. This review covers recent progress in regulating thermal emission through metasurfaces and their applications in infrared sensing, radiative cooling, and thermophotovoltaic devices. Key topics include: 1. **Wavelength-Selective Thermal Emission**: Metasurfaces, such as metal-insulator-metal (MIM) structures and multi-resonant meta-atoms, have been designed to achieve narrowband and broadband thermal emission. 2. **Angular Dependence of Thermal Emission**: Mechanisms like critical coupling, plasmon-phonon coupling, and Fano resonance have been explored to control the angular response of thermal emission. 3. **Polarized Thermal Emission**: Linearly and circularly polarized thermal emission have been achieved using metasurfaces with antenna designs, grating structures, and chiral metasurfaces. 4. **Coherent Thermal Emission**: Techniques to enhance spatial and temporal coherence, such as coupling to surface-phonon polaritons (SPhPs) and surface-plasmon polaritons (SPPs), have been developed. 5. **Dynamic Tunable Thermal Emission**: Active materials like graphene and phase change materials (PCMs) have been integrated with metasurfaces to enable dynamic modulation of thermal emission properties. 6. **Nonreciprocal Thermal Emission**: Violation of Kirchhoff's law through magneto-optical materials and magnetic Weyl semimetals has been explored for advanced thermal management applications. 7. **Near-Field Thermal Emission**: Near-field thermal emission, which exceeds the blackbody limit, has been studied for enhanced heat transfer and energy harvesting. These advancements have opened new avenues for infrared applications, including passive radiative cooling, thermophotovoltaic devices, thermal camouflage, thermal imaging, and biochemical sensing. The review highlights the potential of metasurfaces in addressing the challenges of thermal management and infrared technology.