BACKGROUND In spite of being a significantly growing segment, there are still problems regarding the nutritional, technological and sensory profiles of gluten-free products. Thus, the combination of a variety of functional ingredients is required in order to achieve the desired product quality. METHODS Three types of flour, chestnut, buckwheat and potato, were chosen in this study because they are all gluten-free, nutritionally richer and technologically more advantageous than wheat flour. They are combined with chia seeds, which are also functional ingredients as they are rich in dietary fibre and unsaturated fatty acids. Therefore, this study aims to evaluate the utilization of chia seeds with chestnut, buckwheat and potato flour in biscuits as overall quality enhancers in gluten-free products. The proximate composition, total phenolic content, antioxidant activity, some biscuit quality parameters and the sensory properties of the samples were investigated, and some changes in these products during storage were monitored and evaluated. CONCLUSIONS According to the results, biscuits with chestnut flour had the highest phenolic content (400.2 mg gallic acid equivalent (GAE) per 100 g dry sample) and total antioxidant activity (155.5 mg Trolox equivalent (TE) per 100 g dry sample). Biscuits with chestnut and chia seeds had the hardness of 30.1 N (p<0.05). In addition, the use of chia seeds significantly increased the overall acceptability and flavour scores according to the sensory analysis results. During storage, chia seeds affected the oxidation stability; however, the fatty acid profile remained almost unchanged, except for the losses in lauric, stearic and α-linolenic acids (p<0.05). In conclusion, the biscuits with chestnut and chia seeds were more attractive than those made with other types of flour, with remarkably better nutritional characteristics and sensory attributes. The study fulfils a need for the growing gluten-free market by combining together the functional nutrients of chia seeds, chestnut flour and buckwheat flour to achieve the nutritionally improved and organoleptically acceptable gluten-free biscuits. Furthermore, this study makes an overall evaluation of the changes in product quality during storage to provide new ideas for an overall innovation in the gluten-free food market.