This study proposes an improved data-directed carrier frequency offset (CFO) estimator for ultra-wideband multi-band orthogonal frequency division multiplexing (UWB MB-OFDM) systems. Our approach is based on two adjacent OFDM symbols which convey the identical information on an UWB-OFDM system. To demonstrate the efficiency of the proposed CFO estimator, comparisons were made with existing data-aided estimators in terms of mean square error.