Peony seed meal (PSM) is a byproduct of peony seed oil extraction, which is rich in protein, phenolics, dietary fiber, etc. In order to utilize this valuable functional material, two kinds of PSM (1 and 2) were pretreated by steam explosion and their nutrient composition and properties were evaluated. The phenolics extracted from treated PSM were complexed with chitooligosaccharide (Phe-COS) by ion cross-linking method. The novel complex Phe-COS was characterized and its bioactivities were estimated. Results showed that the content of soluble dietary fiber and total phenolics of PSM were significantly increased by steam explosion (p < 0.05), while the crude fiber and protein of PSM weren’t change much. The total phenolics content of PSM 1 and PSM 2 were increased by 3.26 ± 0.36 mg GAE/g and 5.04 ± 0.58 mg GAE/g respectively, resulting in an enhanced antioxidant activity of PSM. Besides, through complexation with COS, the antioxidant and antibacterial properties of PSM phenolics were greatly enhanced, which attributed to the hydrogen bonds formed between hydroxyl group of phenolics of PSM and COS (p < 0.05).