A study conducted to assess the faunal diversity in Gorai creek of Mumbai, India during August 2019 to July 2020, revealed 90 species of fauna under 70 genera, 50 families, 29 orders, 6 classes and 3 phyla. The order-wise representation of identified fauna was found to be 7 ichthyofauna, 4 pelecypods, 6 gastropods, 2 cephalopods, 1 shrimp and 1 stomatopod along with 8 avifauna. The data collected month wise were pooled together and transformed into three seasons [Monsoon (June to September), Winter (October to February), and Summer (March to May)] and this seasonal data were used for the study of biodiversity pattern. Using the average seasonal species occurrence data as input the following biodiversity indices, S, N, d, J', Brillouin, Fisher, ES(1), H'(loge), 1-Lambda, N10, Delta, Delta*, Delta+, sDelta+, Lambda+, Phi+ & sPhi+ were calculated by using PRIMER Vers. 7.0. The results of the present study indicates that Gorai creek ecosystem is endowed with moderate biodiversity that needs to be conserved.