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Getting the direct methanol fuel cell (DMFC) closer to mass production requires the creation of a high-performance and long-lasting proton exchange membrane (PEM). In this study, self-healable PEMs, Nafion-poly(vinyl alcohol)/phosphotungstic acid (N-PVA/HPW), were prepared through a simple freezing–thawing method. HPW acted as proton conductors, while PVA with reversible hydrogen bonds contributed to the self-repair ability of the membrane. The proton conductivity of the N-PVA/HPW membranes was found to be comparable to that of the pristine Nafion membrane owing to the additional proton-conducting sites and improved water retention provided by the HPW. Along with this, the packed structure of the mixed-matrix membranes led to a lower methanol permeability in all the N-PVA/HPW membranes compared to recast Nafion. As a result, N-PVA/HPW20 membrane with acceptable proton conductivity (0.062 S cm−1) and reduced methanol permeability (2.75 × 10−6 cm2 s−1) achieved the highest selectivity, where selectivity is a well-known indicator of a membrane's suitability for use in DMFC. The N-PVA/HPW20 membrane successfully recorded a peak power density of 2.7 mW cm−2, which is 10.7% higher than the value of recast Nafion. Another highlight of these mixed-matrix membranes is their ability to recover up to 93% of their initial methanol barrier properties after being damaged. This fascinating self-healing property of the membrane is believed to have the potential to extend the service life of DMFC. [ABSTRACT FROM AUTHOR]