This study investigates the effects of hydrolysates from Pseudosciaena crocea roe on the physical and oxidative stability of oil-in-water emulsions, emphasizing the structure-activity relationship between peptide structure and emulsifying properties. The results showed that, compared to other proteases, hydrolysates prepared with papain (PCRHs) at moderate degrees of hydrolysis (DH 4.68% and 6.8%) exhibited superior emulsifying activity index (EAI) and emulsifying stability index (ESI). PCRHs with DH of 4.68%, 6.8% formed smaller particle sizes (89.8 ± 3.52 nm, 112 ± 2.65 nm) and more stable emulsions. EAI and ESI of PCRHs were significantly negatively correlated with emulsion particle size and significantly positively correlated with surface hydrophobicity, amino acid composition, relative molecular mass, random coil content and total sulfhydryl groups. Additionally, although PCRHs with DH of 4.68% produced smaller and more stable emulsion particles, PCRHs with DH of 6.8% significantly inhibited primary and secondary lipid oxidation products formation. Correlation analysis revealed that emulsions with smaller particle sizes exhibited poorer oxidative stability, and secondary volatile oxidation products better reflected the oxidative stability of emulsions. Therefore, hydrolysates from Pseudosciaena crocea roe protein with moderate hydrolysis, particularly PCRHs with DH of 6.8%, demonstrate potential as natural emulsifiers to maintain the physical and oxidative stability of oil-in-water emulsions.