As a novel functional dairy product, yogurt was produced from mixtures of skimmed milk and chestnut milk using probiotic culture. The survival of probiotic bacteria, antioxidant capacity, total phenolic content, and gamma‐ amino butyric acid (GABA) content of the samples were determined. Results showed that sample with chestnut milk 100% contained a higher dry matter, fat, carbohydrate, and caloric value and lower vitamin C, and E contents. Samples had high K, Ca, P, Na, and Na values. Probiotic bacteria were capable of growing well and over the recommended therapeutic value in yogurt with fortified chestnut milk. The yogurt samples showed excellent 2,2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid) and 2, 2′‐diphenyl‐1‐picrylhydrazyl radicals scavenging activities as well as ferric reducing antioxidant power. However, it was found that as the chestnut milk ratio of samples increased, the antioxidant capacity values increased. GABA values of samples varied from 0.31 to 2.43 mg 100 g−1. According to hierarchical cluster analysis, the samples with 20%, 30%, 40%, and 50% chestnut milk had similar compositional properties. Novelty impact statement The objective of the present study was to compare the nutritional, microbiological, and antioxidative properties of probiotic yogurts manufactured using skimmed milk and chestnut milk. Based on the findings of this study, the fortification of chestnut milk, in general, had positive effects on the nutritional properties of probiotic yogurt. The present study describes that yogurt with chestnut milk could be considered a potential source of antioxidant compounds as well as GABA. Chestnut milk‐fortified dairy products could be contributed to ensure maximum functional benefits from these products and present a good alternative for consumers demanding healthier foods.