The noble metal decorated photocatalytic materials have received marvelous attention in recent decade owing to their exceptional applications in energy conversion and environmental remediation. Herein, we have successfully fabricated Au decorated phosphorus doped graphitic carbon nitride (Au/P-CN) photocatalyst for the first time via ionic liquid and in situ photo-reduction methods. The resultant photocatalyst exhibits significant visible light activities for water splitting to evolve H-2 and CO2 conversion to CH4. The amount of H-2 evolved over Au/P-CN photocatalyst is 97 mu mol, similar to 12-fold enhanced compared to that of the bare CN (8 mu mol). Similarly, the amount of CH4 produced over Au/P-CN photocatalyst is 24 mu mol, about 6-fold enhanced compared to that of the bare CN (4 wool). The calculated quantum efficiencies for H-2 evolution and CH4 production are similar to 3.60% and similar to 2.83%, respectively at lambda = 420 nm. The exceptional photocatalytic activities are attributed to the extended visible-light absorption and improved charge carriers separation via the dopant induced surface states and the well decorated Au nanoparticles. This work demonstrate that the Au decorated CN-based photocatalysts show promising applications in photocatalysis for water splitting to evolve H-2 and CO2 conversion to CH4 under visible-light irradiation.