Nanoflakes of two-dimensional (2D)-layered molybdenum diselenide (MoSe2) were used in zinc oxide (ZnO)-based dye-sensitized solar cells (DSSCs) to improve the charge transport by minimizing the recombination loss. The present study demonstrates that photovoltaic performance of the DSSCs can be improved up to ~ 87%. Introducing MoSe2 into ZnO in DSSCs integrates benefits in terms of both electrical and optical as it improved the absorption and charge transport. MoSe2 nanoflakes into nanostructured ZnO did not change anything significantly in terms of surface morphology as they are atomically thin. Specifically, incorporation of 0.65 weight % of MoSe2 into ZnO increased short-circuit current density of the DSSC by ~ 70% (from 4.7 to 8 mA.cm−2) due to an effective optical absorption in the spectral range of 350–800 nm with two characteristic peaks at 550 nm and 670 nm. Further, it was also attributed to the presence of MoSe2 flakes in ZnO, which constituted efficient charge transport pathways, in terms of dangling-bond free surface, through which electron transport occurred with minimum possible loss. It was also noticed that variation in MoSe2 quantity in ZnO plays a critical role in DSSC performance. [ABSTRACT FROM AUTHOR]