The high sensitivity FSK radiofrequency signal receiver includes an antenna for receiving FSK radiofrequency signals, a LNA amplifier receiving signals picked up by the antenna, a local oscillator for supplying oscillating signals, a mixer for mixing the incoming signals with the oscillating signals to produce intermediate signals. The receiver includes a broadband or poly-phase filter for filtering the intermediate signals, and a sampler for supplying sampled intermediate signals to a high sensitivity demodulation stage, which supplies data signals. The receiver includes a processing circuit for performing a discrete Fourier transform of sampled intermediate signals. The selector at the processing circuit output determines the difference between the signal amplitude peak frequency above a determined threshold and the expected frequency of the intermediate signals. The frequency difference enables for correcting the oscillating signals frequency, to enable the demodulation stage to demodulate the data in the sampled intermediate signals and supply data signals.