In the present study, shape controlled flat square shaped silver nanoplates (SNP’s) were synthesized using aqueous extract of watermelon rind which was regenerated after biosorption of heavy metal ions. The formation of silver nanoparticles was visually confirmed by change in color from yellow to brown and was further confirmed by absorption peak at 465 nm in UV–Visible spectrophotometer. Synthesized SNP’s were characterized using FTIR, XRPD and TEM analysis. TEM analysis revealed the formation of flat and square shaped SNP’s with size less than 50 nm. FTIR analysis further supported the reduction and binding of phytochemicals chemicals present in watermelon rind extract. These SNP’s were tested for the antimicrobial activity against both gram positive bacteria Micrococcus luteus (ATCC 10240) and Staphylococcus aureus (ATCC 29213) , gram negative bacteria Salmonella typhi (ATCC 6539) and Klebsiella pneumonia (ATCC 13883). SNP’s showed good antimicrobial activity against these microbial cultures. The results suggest that regenerated watermelon rind has the capability to synthesize SNP’s with antimicrobial properties.