Myofibrillar protein microgel particles (MMP) are promising Pickering stabilisers due to their structure and delivery potential. However, their fibrous, irregular shape promotes aggregation, limiting practical use. This study investigated the effect of xanthan gum (XG) concentration (0.025–0.4%) on MMP dispersion in water and its role in stabilising Pickering emulsions. FTIR and interaction analysis revealed that hydrophobic interactions dominate between XG and MMP, followed by hydrogen bonding and electrostatic forces. At higher XG concentrations (0.2–0.4%), complex particle size decreased from 5.21 μm to 4.49 μm, the contact angle increased from 57.67° to 77.33°, and a uniform dispersed state was achieved. Although increasing XG gradually reduced the emulsifying activity of MMP, it significantly improved the emulsion stability. Microstructure analysis showed that at low XG concentrations, emulsions exhibited phase separation. Rheological measurements indicated that XG-MMP complexes increased continuous-phase viscosity and shear resistance, enhancing macroscopic stability. In summary, at a critical XG concentration of 0.2%, the emulsion undergoes a transition from aggregation-driven instability to network-mediated stabilisation, achieved through the interfacial layer with spatial confinement by a weak aqueous-phase network. This work provides a theoretical foundation and a practical design strategy for fabricating highly stable, tuneable Pickering emulsions based on protein microgel particles.