Carbon quantum dots (CQDs) have attracted growing interest due to their superior luminescent properties, which make them excellent photosensitizers for TiO2. This study presents the green-synthesis of CQDs from edible mushroom Agaricus bisporus through microwave irradiation. In the study as-synthesized CQDs were used as a sensitizer for TiO2 in photocatalytic hydrogen evolution in aqueous triethanolamine (sacrificial reagent) under visible-light irradiation. Photocatalytic hydrogen production activity of CQD-sensitized TiO2 was found to be 472 μmol g−1 h−1 (without loading any noble metal co-catalyst) and 1458 μmol g−1 h−1 (with loading Pt co-catalyst). The study revealed that the CQDs from mushroom A. bisporus can be used as an efficient sensitizer for TiO2 in photocatalytic hydrogen production.