The rapid development of electronic equipment has led to stricter requirements for thermal management materials. Traditional polymeric composites cannot satisfy these demands due to their low thermal conductivity (TC). The rapid development of two-dimensional (2D) nanomaterials with high intrinsic TC provides us with a new avenue to prepare highly thermally conductive composites. In our work, small amounts of exfoliated Ti3C2Tx nanosheets were chosen to cooperate with boron nitride nanosheets to fabricate hierarchically layered composite films by vacuum-assisted filtration. We found that small amounts of Ti3C2Tx reform the in-plane TC of the composite film. Our experimental results show that when the mass content of Ti3C2Tx in the hybrid fillers is 5%, this composite film possesses an exceptionally high in-plane thermal conductivity up to 52.4 W m−1 K−1 and still maintains the favorable electrical insulating property. Besides, more interestingly, the small addition of Ti3C2Tx can simultaneously improve the tensile strength and the fracture strain of the film. We attribute the enhancement of thermal-conducting performance to the well-designed interface assembled by MXene. Therefore, this freestanding composite film has immense applied value in highly integrated electronic devices.