The development of innovative solid particles from renewable resources possessing high biocompatibility and exceptional emulsification capabilities is crucial for stabilizing Pickering emulsions and advancing carrier systems. In this study, a pea protein isolate (PPI)-cellulose conjugate particle was prepared by the Maillard reaction. Compared to the isoelectric point of pH 4.6 of pure PPI, the isoelectric point of these conjugate particles decreased to pH ∼1. The prepared conjugates could stabilize Pickering emulsions with a high oil phase content (65%), and the prepared emulsion demonstrates long-term storage stability (more than 5 weeks), pH stability (stable from pH 5 to 9 for at least 14 days), and thermal stability (maintained at 80 °C for 48 h). Furthermore, the emulsion demonstrates good protective capabilities for curcumin, with its activity decreasing by only 10% after storage for 10 days. Therefore, the prepared emulsions can be widely used in various fields, such as the food, cosmetic, and pharmaceutical industries.