To achieve high-value utilization of fish processing by-products and to develop novel collagen peptide-based foods, this study prepared sturgeon swim bladder collagen peptides by biomimetic enzymolysis. The resulting peptides were then used to produce a blueberry-collagen peptides beverage through fermentation with Kluyveromyces marxianus. The final product had a viable bacterial count of 1.43 × 10? CFU·mL-1, with L*, a*, and b* values of 24.24, 8.72, and –0.96, respectively. It contained 14.55% collagen peptides and 25.77% soluble solids, along with a pH value of 4.46 and a titratable acidity of 1.51 g/100 mL. The contents of total phenolics, flavonoids, and anthocyanins were 147.05 mg GAE/100 mL, 113.63 mg RE/100 mL, and 19.70 mg CGE/100 mL, respectively. Characteristic volatile compounds identified in the beverage included ethyl acetate, isoamyl acetate, phenethyl acetate, hexyl acetate, and linalool. Additionally, it exhibited a bright purplish-red color, a uniform and stable texture, a well-balanced sweet-and-sour taste, a rich and harmonious aroma, and achieved an overall impression score of 82.34 and an affective test score of 84.20. This study provides a new approach for the high-value utilization of fish processing by-products, and the development of flavor-oriented, healthy collagen peptide-based foods.