Monomethyl auristatin E (MMAE) is a derivative of the marine peptide Dolastatin 10, which has therapeutic effects against various cancers according to its antimitotic activity in multiple clinical trials. The antibody drug conjugate (ADC) of MMAE is currently used in clinical practice. However, the safety issues of MMAE-based ADC, such as high drug toxicity and poor bioavailability, still exist when using it for anticancer therapy. A sustained release of drug delivery approach should be used to reduce toxicity and achieve sufficient anticancer effects. Herein, PLGA-b-PEG2000 with excellent biocompatibility and slow degradation ability was adopted to construct MMAE-loaded nanoparticles for safe and effective chemotherapy. The sustained release effect and the immunogenic cell death (ICD) effect of PLGA-MMAE nanoparticles were assessed by in vitro experiments. The PLGA-MMAE nanoparticles effectively accumulated in the tumor through the enhanced permeability and retention (EPR) effect, inducing cell apoptosis and causing a certain degree of immune response. The sustained drug release of PLGA-MMAE improved the bioavailability and effectively reduced the toxicity and development of the tumor compared to the effect of free MMAE or ADC. Overall, this study provides a safe and effective chemotherapeutic approach, as well as a simple and effective synthetic process for MMAE-based nanoparticles, improving their therapeutic efficacy and safety.