Inadequate information on the diversity and dispersion of desmids has led to incomplete floristic data in the northeastern region of India. The present study focuses on contributing to the information on the diversity and geographical distribution of desmid in water bodies of the Brahmaputra River basin of the Indian subcontinent. During the period 2019–2022, desmid flora of 91 waterbodies were studied. Two-hundred-and-thirty-one taxa belonging to five families and 25 genera were recorded, out of which 94 were new records for the northeastern India. Desmidiaceae was the dominant family with 195 species and with 69 species Cosmarium was the dominant genus.