This study aims to establish the intrinsic link between the high-temperature rheological behavior and kinetic relaxation characteristics of La-based metallic glasses. By conducting dynamic mechanical analysis and high-temperature tensile strain-rate jump experiments on three La-based metallic glasses with significant β relaxation, and combining the findings within the free volume theory framework, their high-temperature rheological properties are investigated systematically. The results show that the steady-state flow stress and activation volume evolution trend are consistent within the normalized temperature range. The average activation energy for high-temperature rheology aligns with the activation energy range of α relaxation, confirming the strong association between rheological behavior and α relaxation. The activation energy for β relaxation shows an opposite trend, indicating that it may precede α relaxation. A dynamic competition between defect annihilation and generation governs the rheological behavior, and kinetic parameters reveal the temperature and strain-rate sensitivity of metallic glasses. This study lays a theoretical foundation for optimizing the high-temperature mechanical properties of La-based metallic glasses and also provides new insights into understanding the coupling relationship between multi-scale relaxation behavior and rheological mechanisms in metallic glasses.