Graphite phased carbon nitride (g‐C3N4) has attracted extensive attention attributed to its non‐toxic nature, remarkable physical–chemical stability, and visible light response properties. Nevertheless, the pristine g‐C3N4 suffers from the rapid photogenerated carrier recombination and unfavorable specific surface area, which greatly limit its catalytic performance. Herein, 0D/3D Cu‐FeOOH/TCN composites are constructed as photo‐Fenton catalysts by assembling amorphous Cu‐FeOOH clusters on 3D double‐shelled porous tubular g‐C3N4 (TCN) fabricated through one‐step calcination. Combined density functional theory (DFT) calculations, the synergistic effect between Cu and Fe species could facilitate the adsorption and activation of H2O2, and the separation and transfer of photogenerated charges effectively. Thus, Cu‐FeOOH/TCN composites acquire a high removal efficiency of 97.8%, the mineralization rate of 85.5% and a first‐order rate constant k = 0.0507 min−1 for methyl orange (MO) (40 mg L−1) in photo‐Fenton reaction system, which is nearly 10 times and 21 times higher than those of FeOOH/TCN (k = 0.0047 min−1) and TCN (k = 0.0024 min−1), respectively, indicating its universal applicability and desirable cyclic stability. Overall, this work furnishes a novel strategy for developing heterogeneous photo‐Fenton catalysts based on g‐C3N4 nanotubes for practical wastewater treatment.