In time-varying mobile channels, the Doppler effect causes intercarrier interference (ICI) in an OFDM system. A lot of research has been found to mitigate the ICI effect in order to improve the system performance. However, ICI reduction algorithms usually require the information of the channel impulse response (CIR) sample by sample. In this paper, we propose a new decision feedback ICI cancellation (DFIC) algorithm with modified decision feedback CIR estimation. The proposed DFIC algorithm uses the time-domain Kalman filter for initial CIR estimation for the coefficients of the DFIC equalizer. Then, the iterative decision feedback loop can be used to enhance the estimation of CIR values such that more accurate coefficients can be obtained. Simulation results show that the proposed ICI mitigation algorithm incorporating decision feedback channel estimation is effective to deal with the ICI in mobile OFDM channels.