A great deal of efforts have been dedicated to reduce carrier recombination problem in β-Ga 2 O 3 using strategies, such as doping, compositing, and interfacing with different materials to enhance device performance. However, reports are rarely available for integrating In with β-Ga 2 O 3 for photoelectrochemical applications. Herein, we reports the effect of In addition in β-Ga 2 O 3 to produce In/β-Ga 2 O 3 nanocomposite for photoelectrocatalysis. The intrinsic sample exhited mixed-phase (α-β)-Ga 2 O 3, whereas the composite showed a mixed-phase β-Ga 2 O 3-indium. A significant amount of In was detected on the heterogenous film, suggesting that doping was exceeded. A significant bandgap narrowing was observed from 4.79 to 4.45 eV upon In incorporation. The presence of In in β-Ga 2 O 3 resulted in a shift in photoluminescence emission from violet to green light. Photoelectrochemical measurements in 0.1 M KOH solution demonstrated a relatively high photocurrent density of 1.720 mA/cm 2 at 1.0 V vs. Ag/AgCl for the In/β-Ga 2 O 3 heterogeneous film.