In this study, grape pomace (GP), a by-product consisting of grape skins and seeds rich in dietary fibres and polyphenols, was used in wafer sheets at different concentrations [5.00 (GP5), 10.0 (GP10), and 15.0 g 100 g(-1) (GP15)] for the partial replacement of wheat flour (WF) and improve the functionality of wafer sheets. The GP inclusion at concentrations higher than 5.00 g 100 g(-1) significantly affected the texture of sheets as well as the flow behaviour of batters, resulting in softer sheets and more viscous batters (P < 0.05). Moisture contents did not significantly change after GP addition (P > 0.05). After the addition of GP, the L* values decreased and the a* values increased, making the wafers darker (P < 0.05). Moreover, under simulated in vitro digestion conditions, the bioaccessibility of total phenolic compounds in saliva, gastric juice, and intestinal juice was significantly higher than control even at the lowest GP concentration (P < 0.05). Regarding sensory properties, only smoothness and crispness were significantly affected by GP addition, and samples were found to be crisper with higher concentrations of GP. In conclusion, it is possible to partially replace the WF in wafers with GP at a concentration of 5.00 g 100 g(-1) to develop a product with higher functionality and nutrient content.