This paper reports on the first demonstration of ultra-fast (thermal time constant, τ ∼80 μs) and high resolution (noise equivalent power, NEP ∼656 pW/Hz1/2) infrared detectors based on high quality factor 50-nm thick aluminum nitride (AlN) piezoelectric resonant nano-plates. For the first time, we show that by employing nanoscale (30 nm) aluminum anchors, both high thermal resistance (Rth ∼9.2×105 K/W) and high quality factor (Q ∼1000) can be achieved in greatly scaled AlN nano-plate resonators. Furthermore, we experimentally demonstrate that the resonant structures are capable of efficiently absorbing short-to mid- wavelength infrared (absorption, η ∼47%, for blackbody radiation at 625 °C) without any additional absorber. These unique features are exploited for the first experimental demonstration of AlN NEMS resonant infrared detectors with highly reduced area (down to 20×22 μm2, comparable to the ones of state-of-the-art microbolometers) and over 4x improved figure of merit (FoM=1/(NEP·τ)) compared to what previously achieved by the same technology.