Aim: We carried out a first biogeographical analysis of Sargassum species in Mexican coasts, to recognize distribution patterns, species richness and the events related with its distribution. Location: Mexican Pacific and Atlantic coasts. Methods: Based on the specialized literature, a search for records of Sargassum species in Mexico was carried out. Subsequently, the records were mapped and two matrices were constructed, one for each coast. From these matrices, a phenogram was obtained with the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) using the Jaccard index. Additionally, in order to recognise complementary areas with conservation potential, a Whittaker’s paired beta analysis was performed. Results: Our results revealed the presence of two very marked patterns between the Mexican Pacific and Atlantic, with five and three distribution areas, respectively. In addition, two biotic convergence zones were identified: the south-central zone of the Gulf of California and the northern zone of the Yucatan Peninsula. These zones coincide with the highest points of species richness of Sargassum, due to oceanographic and climatic conditions that are strengthened by the study of other species. A transition zone is recognized in the state of Tamaulipas, and an isolation zone for the state of Campeche. Main Conclusions: The patterns observed can be explained throughout the complex geological history of the Mexican territory and also offers an explanation of the processes of adaptive radiation that has given rise to the species of the genus.