The marine gravity field is one of the fundamental components in geodesy, marine geophysics, geoid determination, and marine navigation. In this study, the performance of six global gravity field models, including EGM2008, EIGEN-6C4, Hust-Grace2016s, XGM2019e_2159, SGG-UGM-2, and WHU-SWPU-GOGR20225, was investigated for simulating free-air gravity anomalies over the southern coasts of Iran, the Oman Sea, and the northern Indian Ocean. Gravity anomalies were computed using the spherical harmonic coefficients of the models, with EGM2008 selected as the reference model for comparison. The results showed that the mean gravity anomalies of the investigated models were very close to each other, ranging from approximately −979015.53 to −979015.56 mGal, indicating a good consistency among the models in representing the long-wavelength component of the gravity field. In contrast, noticeable differences were observed in the range and spatial variability of the gravity field. The Hust-Grace2016s model, with a maximum degree of 160, produced a smoother gravity field, whereas models with higher development degrees, particularly XGM2019e_2159, represented greater spatial details. Comparison of the results at development degrees of 160, 720, and 2190 further showed that part of the observed differences among the models is associated with their harmonic development degree, while the remaining differences can be attributed to differences in input data and modeling approaches. The results indicate that the selection of an appropriate gravity field model should be consistent with the intended application; smoother models are more suitable for navigation applications, whereas models providing greater spatial detail are more appropriate for studies of seafloor structure.