Paclitaxel spirulina nanoparticles were said to have promising anticancer activity against gastric cancer. Nanoparticles of paclitaxel-spirulina were prepared for treating gastric cancer using precipitation technique. The synergistic anticancer efficiency againstMKN45 cells retains when the paclitaxel and spirulina were encapsulated into nanoparticles. To increase the site specific delivery, intra-tumoral administration was carried in the in vivo evaluation. There was an increase in overall survival in an MKN45-transplanted mice model and notable improvement in anti-tumour efficacy when paclitaxel-spirulina nanoparticles were delivered through intra-tumoral administration. The further investigation of overall anticancer mechanism of these nanoparticles is made as a major part in this research. Hence, the conjecture of this research is that, the paclitaxel-spirulina encapsulated nanoparticles could be an effective chemotherapeutic formulation for gastric cancer.