Swordfish (Xiphias gladius) is a highly migratory fish whose habitat suitability is significantly influenced by the marine environment, and the prediction of its habitat using changes in the marine environment is of great scientific importance. In this study, we used the catch information of swordfish in the Chinese Indian Ocean Longline Fisheries Observer Data from 2017 to 2019 as species occurrence data, combined with the environmental data in the western Indian Ocean waters, including sea surface temperature (SST), sea surface height (SSH), chlorophyll a (Chl a) concentration, mixed layer depth (MLD), and sea surface salinity (SSS), the habitat suitability distribution of swordfish in the western Indian Ocean is simulated by using a maximum entropy model (MaxEnt). Model results show that: (1) the model has very high accuracy in simulating the habitat suitability distribution of swordfish in the western Indian Ocean, with AUC values greater than 0.9 in all seasons, and can be used to simulate the potential habitat suitability distribution of swordfish; (2) changes in the distribution of suitable habitat for swordfish in the study area are generally consistent with changes in the actual operational location, and the distribution of areas with high habitat suitability for swordfish is more concentrated in both the dry and rainy seasons, but the distribution range is greater in the wet season than in the dry season; (3) SST, SSS and MLD are important environmental factors affecting the habitat suitability distribution of swordfish in the western Indian Ocean. The optimum ranges of SST, SSS and MLD in the dry and rainy seasons are 25.8−31.6°C, 34.4−35.9 and 0.1−24.9 m, and 25.6−30.5°C, 34.8−36.4 and 13.1−54.1 m, respectively. The results of the study provide essential reference information for the sustainable use and scientific management of swordfish populations in the western Indian Ocean.