<p>Two-dimensional transition metal carbides/nitrides (MXenes) exhibit outstanding mechanical and electrical properties, making them highly promising for applications across various fields, including electronics, aerospace, energy storage, etc. However, it remains challenging to assemble MXene nanosheets into high-performance macroscopic nanocomposites primarily due to the low-stress transfer efficiency between nanosheets. We have discovered that the presence of voids within MXene-based nanocomposites usually plays a key role in enhancing their performance. In this review, we systematically discuss the impact of voids on the performance of MXene-based nanocomposites and subsequently present strategies for reducing the voids, including synergistic interfacial interactions, nanosheets filling, optimization of the fabrication process, nanoconfined assembly, and more. Finally, we provide an outlook on the challenges and outline a roadmap for the fabrication of high-performance MXene-based nanocomposites.</p>