Herein, a series of N-doped Ti₃C₂/porous g-C₃N₄ composites are ultrasonically prepared from N-doped Ti₃C₂ and porous g-C₃N₄ under N₂ atmosphere. The structure, morphology, and optical characteristics of the as-prepared composites are characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, etc. Moreover, photocatalytic measurements show that N-doped Ti₃C₂ is an excellent modifier for porous g-C₃N₄ to heighten its photocatalytic activity. Only 44.1% of rhodamine B can be degraded by the photocatalysis of pristine porous g-C₃N₄, while the photocatalytic degradation ratio of rhodamine B can reach up to 97.5% for the optimal N-doped Ti₃C₂ loading composites under visible light for 15 min. Moreover, the photocatalytic tests of N₂ fixation confirm that the optimal composites show the highest production yield of NH₄⁺ (11.8 μmol g_cat⁻¹ h⁻¹), which is 2.11-folds more than that of porous g-C₃N₄ (5.6 μmol g_cat⁻¹ h⁻¹). The reinforced photocatalytic properties are revealed to profit from the more photogenerated electrons and holes’ separation, higher ability for light response, and more abundant active sites. This work develops the route for boosting the photocatalytic properties of porous g-C₃N₄ with N-doped Ti₃C₂.