<p>In marine engineering, the inherent sound absorption capabilities of polymeric materials are often limited, necessitating the incorporation of nanofillers to optimize both mechanical and acoustic properties of underwater sound-absorbing composites. In this study, Ti₃C₂T_x was modified using polyvinylpyrrolidone (PVP) alone or synergistically with cetyltrimethylammonium bromide (CTAB), yielding PVP-modified Ti₃C₂T_x (PVP/Ti₃C₂T_x) and PVP/CTAB-modified Ti₃C₂T_x (PVP/CTAB/Ti₃C₂T_x). These modified fillers were integrated with thermoplastic polyurethane (TPU) via a solution blending method to fabricate Ti₃C₂T_x/TPU, PVP/Ti₃C₂T_x/TPU, and PVP/CTAB/Ti₃C₂T_x/TPU nanocomposites. Comprehensive characterization using FT-IR, XRD, XPS, scanning electron microscopy and transmission electron microscopy confirmed that CTAB not only achieved effective surface modification of Ti₃C₂T_x but also cooperated with PVP to form a complex intercalated structure. Mechanical, dynamic mechanical, and underwater acoustic tests revealed uniform dispersion and excellent compatibility of the modified Ti₃C₂T_x within the TPU matrix. The composites exhibited simultaneous reinforcement and toughening effects, particularly with the addition of only 2 phr (parts per hundred rubber) PVP/CTAB/Ti₃C₂T_x, which increased tensile strength and elongation at break by 59.7% and 34.6%, respectively, compared to pure TPU. The composites incorporating Ti₃C₂T_x and its modified variants demonstrated superior underwater sound absorption performance, with sound absorption coefficients exceeding those of pure TPU. Notably, the PVP/CTAB/Ti₃C₂T_x/TPU composite achieved a 71.4% improvement in average sound absorption coefficient and exhibited enhanced performance at lower frequencies (below 1–3&#xa0;kHz), particularly at 1.8&#xa0;kHz, where its coefficient surpassed pure TPU by 0.23. This study provides novel insights for the development of advanced underwater sound-absorbing composites.</p>