Recently, designing a nanocarrier for carboplatin with high retention power and entrapment efficiency and its corresponding impact has sparked a heated debate. The aim of this study was to investigate the cytotoxic efficacy of the biodegradable nanocarrier loaded with carboplatin. This study focuses on (i) characterization, (ii) in vitro drug release evaluation, and (iii) cytotoxicity of liposome nanoparticles (NPs) loaded with carboplatin. The reverse-phase evaporation was used to synthesize nanoparticles and determine specifications including shape morphology, particle size, drug release rate, polydispersity index (PDI), stability, and zeta potential of prepared formulation. Furthermore, A172 and C6 glioblastoma cell lines were used to determine the efficacy of nanodrug using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay. NPs had an average size of 240.5 nm and zeta potential of − 25.8 mV. Drug loading and encapsulation efficiency of NPs were 2.65% and 71.45%, respectively. Moreover, entrapment efficiency and drug release rate increase in a time-dependent manner. The results reveal that the preparation method and PEGylation have a positive effect of the properties of NPs and the efficiency of encapsulation and loading rate. Results from stability study reported that using PEGylation helps to improve characteristics of NPs and results in minimal changes in their properties over the time. In addition, our data demonstrate that carboplatin cytotoxicity correlates with drug concentration which was considerably increased in NPs. PEGylated NPs have enhanced cytotoxicity against glioblastoma cell lines compared with free drug. Overall, our evaluation has shown that the PEGylated nanoliposome particles loaded with carboplatin hold high potential for nanoparticle-based therapy.