A novel numerical inverse Fourier transform algorithm for the lightning-related electromagnetic transient analysis is presented in this paper. For the inverse Fourier transform, first the frequency domain response is sampled using a non-uniform sampling approach and approximated by the vector fitting method, leading to a representation in the form of rational function. Then, by solving the inverse integral with analytical integration, it is possible to obtain a continuous time-domain transient solution. The validity of the proposed method is confirmed by some numerical examples in the published literature, where a comparison with other existing methods is made, i.e., the linear interpolation-based and the exponential interpolation-based techniques. The proposed algorithm provides an effective tool for transient analysis involving the transformation of transient waveforms from the frequency domain into the time domain.