Recent advances in CubeSat technologies have enabled use of radiometers deployed in constellations of these small satellites for Earth and space science missions. Advantages of CubeSats such as their low cost, low mass and volume, and lower power requirements, however, are confronted by the challenges in calibration of their payloads as well as intercalibration of CubeSat constellations due to higher sensitivity to ambient conditions. This paper describes a novel system-level calibration framework, called “ACCURACy” to calibrate CubeSat based radiometer constellations as a single system in their entirety with minimal errors and uncertainties. Artificial constellation simulations have demonstrated that ACCURACy, while maintaining the accuracy levels of ideal calibration scenarios, leads to lower uncertainties in calibrated radiometer products compared to state-of-the-art calibration and intercalibration techniques based on overlapping measurements of the constellation members.