This investigation presents pioneering discoveries concerning the endemic seaweed Ulva ovata across multiple sites in the Gulf of Khambhat, India, going beyond its type locality, Gopnath. The primary objective of this research was to examine the substrate type and various environmental factors affecting seaweed diversity at five sites where endemic U. ovata was found. Identifying 11 seaweed species under Chlorophyta and Rhodophyta phyla, the study highlights rocky sites exhibiting higher Simpson (D) and Shannon (H ') diversity indices, species richness, and percentage cover during cold months. k-dominance analysis indicates more species at Pingaleshwar, Unchakotda, and Gopnath. Bray Curtis similarity shows similarity in seaweed composition between Unchakotda-Pingaleshwar, and Kuda-Khadsaliya, whereas Gopnath forms a different cluster mode. Key species U. rigida and U. ovata, identified by SIMPER analysis, act as bio-indicators for future studies. Five sites demonstrate distinct seawater temperature, dissolved oxygen, light intensity, salinity, total dissolved solids (TDS), electrical conductivity (EC), wind velocity, UV index, nitrate (NO3-), and nitrite (NO2-) significantly impacting seaweed diversity. This study enhances understanding of seaweed distribution and environmental influences in the Gulf of Khambhat, offering insights into ecological dynamics and implications for marine conservation and management strategies.