A convenient polarization independent, broadband femtosecond optical gating technique utilizing transient Kerr lens effect is demonstrated by measuring the chirp structure of linearly polarized or non-polarized white light continuum generated in water and a photonic crystal fiber, respectively. Comparing with previous time-resolved spectroscopic techniques, this Kerr lens gating method is not limited by the requirement of specific nonlinear media with broadband response, critical phase-matching conditions, and especially the pump-probe polarization relationship. By replacing the white light continuum with other broadband light signals of interest, this method can be exploited in other femtosecond time-resolved spectroscopy, e.g., femtosecond photoluminescence.