Based on the external and internal morphologies, a total of 50 species of marine benthic algae belonging to 19 families of 11 orders collected along the Kalegauk island from September 2016 to January 2017 had been identified. Except the Gelidium arenarium Kylin, Catenella nipae Zanardini, Gracilaria verrucosa (Hudson) Papenfuss and Rhizoclonium riparium (Roth) Harvey which were described in the previous reports of Kalegauk I. by Kyaw Soe and Kyi Win (1977), the remaining species were firstly reported for the diversity of marine algae of Kalegauk Island. Moreover, Catenella caespitosa (Withering) Irvine in Parke & Dixon (= Catenella opuntia (Goodenough & Woodward) Greville), Polysiphonia atlantica Kapraun & Norris (= P. macrocarpa Harvery) and P. howei Hollenberg (= P. rhizoidea Menez) and Rhizoclonium curvatum Chapman were firstly recorded for the diversity of marine algae of Myanmar after Soe-Htun et al. (2009). The distributional ranges of each species found along the coastal areas of the Kalegauk Island and the distributional ranges of those found along the three Coastal Regions of Myanmar were recorded. A brief note on potential uses of each species was presented.