Demonstrated first ultrafast, spectrally-selective thermal photodetector. Utilized metasurfaces to create spectrally-selective perfect absorption enabling the use of an only 100 nm pyroelectric thermal detection layer and revealing speeds of <700 ps, an improvement of five-orders-of-magnitude over state-of-the-art. The metasurface also acts as an on-chip spectral filter promising for hyperspectral imaging (Nature Materials 19, 158 (2020)).