Er³⁺–TiO₂ synthesized by a surfactant free hydrothermal method exhibits good photoactivities under sun-like excitation for the degradation of phenol. The presence of Er³⁺ does not affect the structural and morphological features of the TiO₂ significantly. The best photocatalytic performance was attained for the samples with 2 wt% of Er. Different photocatalytic runs indicated that the incorporation of the Er³⁺ cation would be responsible for the enhanced photocatalytic activity, which participates in different mechanisms under UV and NIR excitation.