Whey and corn oligopeptides are by-products from cheeses and cornstarch manufacturing processes respectively. Both of these by-products are highly nutritious. It was found in our previous research that some lactic acid bacteria (LAB) can utilize l-glutamate in corn oligopeptides to produce γ-aminobutyric acid (GABA). Moreover, research have shown blood-pressure-lowering effect of GABA-enriched dairy foods. Therefore, the objective of this study is to develop a GABA-enriched fermented compound beverage made up of whey and corn oligopeptides. Four species of LAB, including Lactobacillus plantarum, Lactobacillus bulgaricus, Streptococcus thermophilus and Lactobacillus acidophilus, were screened as single starter or mixed as compound starter. The quantity of substrates were characterized with viable counts and yield of GABA as evaluation indicators. Results showed that the optimal starter was L. plantarum J26 and the optimal substrates were 8% whey powder and 4% corn oligopeptides. In addition, the optimization of initial pH value, fermentation temperature and time were carried out using Box-Behnken response surface methodology. The optimal conditions of fermentation were 68 h fermentation at 32°C with an initial pH 5.4. The content of GABA reached 180.4 mg L⁻¹ in the beverage which had significant difference (P ≤ 0.05) compared with beverage fermented by other starters under same conditions, and it was far above the GABA content of unfermented beverage (12.0 mg L⁻¹). Furthermore, the viable counts of L. plantarum J26 were beyond 8.0 log cfu mL⁻¹. At last, the yield of GABA and viable counts were 155.2 mg L⁻¹ and 7.6 log cfu mL⁻¹ which were declined slightly (P > 0.05) during storing at 4°C for 21 d. Sensory evaluation was done after the fermentation and during the whole storage. In general, results showed that the beverage received an equal or higher degree of overall hedonic sensory score comparing with commercial compound milk beverages.