Liposomes have been widely utilized as drug carriers to achieve the efficient tumor accumulation of anticancer drugs through the enhanced permeability and retention effect. However, due to their rigid lipid membranes, drug release from liposomes is limited in tumor tissues, thereby compromising anti-tumor efficacy. Therefore, the development of technologies that selectively promote drug release from liposomes in tumors is required. We previously demonstrated that polyethylene glycol (PEG)-modified sorbitan monooleate (Span 80) niosomes (PEG-Span 80 niosomes) enabled the triggered release of doxorubicin from the aqueous core of PEG-modified liposomes (PEG-liposomes). In the present study, we investigated whether PEG-Span 80 niosomes also promote the release of paclitaxel (PTX) from the lipid bilayer of PEG-liposomes. In addition, the triggering effect of PEG-modified sorbitan trioleate (Span 85) niosomes (PEG-Span 85 niosomes) on PTX release from PEG-liposomes was evaluated. PTX release from PEG-liposomes was significantly enhanced from early time points in the presence of PEG-Span 80 niosomes, and the amount released at 48 h was approximately 3.9-fold larger than that in the absence of PEG-Span 80 niosomes. Moreover, PEG-Span 85 niosomes promoted PTX release from PEG-liposomes, and the amount of PTX released in the presence of PEG-Span 85 niosomes was approximately 2.1-fold larger than that in the presence of PEG-Span 80 niosomes. In addition, the triggered release of PTX from PEG-liposomes induced by PEG-Span 85 niosomes was partially attributable to membrane fusion between these particles. These results provide valuable information for the realization of safe and effective liposome-based cancer chemotherapy.