Kalmi Shak or water spinach (Ipomoea aquatic) is a Bangladeshi indigenous green leafy vegetable and herbaceous aquatic or semi aquatic perennial plant. A primary study was conducted to elucidate the multi functionalities of this vegetable. Extract of Kalmi Shak exhibited high antioxidant properties with hydrophilic-oxygen radical absorbance capacity (H-ORAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity being 341.92 ± 1.32 and 37.67 ± 2.63 µmol Trolox equivalent / gram of dry weight (TE/g DW), respectively. The total polyphenols content was estimated to be 12.56 ± 0.08 mg gallic acid equivalent / gram of dry weight (mg GAE/g DW), and moisture content was found to be 85%. The extract also showed anti-mutagenic effect on Trp-P2 induced mutagenicity to Salmonella Typhimurium TA98, and anti-tumor activity to mouse myeloma cell line P388. The extract of this vegetable also exhibited anti-bacterial activities against several spoilage and pathogenic bacteria. The multi functionalities, economic price and availability during the entire year have made this indigenous Bangladeshi vegetable important from both medicinal and industrial aspects.