The green synthesis of inorganic metal oxide nanoparticles is essential because it reduces environmental impact and enhances biocompatibility by using eco-friendly materials and processes. This sustainable approach also minimizes hazardous chemicals, promoting safer and cleaner production methods. The sodium alginate-Pluronic F127-modified SnO2 (SAPFSO) NPs were prepared using the green method using Psidium guajava leaf extract. The SAPFSO NPs exhibit a tetragonal rutile structure from the X-ray diffraction patterns. The FESEM and EDAX spectra identified the morphology and chemical composition. The Sodium Alginate, Pluronic-F127, and SnO2 functional group vibrations can be seen in the FTIR spectra. The DLS spectra and hydrodynamic sizes of SAPFSO NPs were observed at 183 nm. The various surface defects of SAPFSO NPs were identified from the PL spectrum. The antimicrobial activity of SAPFSO NPs was tested against gram-positive and gram-negative strains such as S. aureus, K. pneumoniae, S. dysenteriae, S. pneumoniae, Bacillus megaterium, Proteus valgaris, and Candida albicans fungal strain using the well-diffusion method. To increase the concentration, SAPFSO NPs also increased the antimicrobial activity. The anticancer activity of SAPFSO NPs tested against the human breast cancer cell line (MDA-MB-237). SAPFSO NPs exhibits potential anticancer activity against triple negative breast cancer cell line. These results support that SAPFSO NPs can be applied in healthcare and industrial settings to improve human health.