Polyvinylidene fluoride (PVDF) has garnered interest due to its piezoelectric property and as a non-toxic, conformable, and low-cost alternative to the popular piezoelectric ceramic. A novel processing method through the combination of thermal and supercritical carbon dioxide (ScCO₂) has been used to successfully promote the formation of electroactive phases (i.e., β and γ phases), as well as its piezoelectric property. In this report, the processing-to-structure properties and mechanisms that affect crystallization behaviors of electroactive phases were elucidated. It was revealed that γ crystal formation was through thermal processing while β phase was nucleated through fast cooling and physical foaming of CO₂ bubbles. The results were comparable to common processing method and literature, with a maximum electroactive crystal phase of 72.2% and a corresponding piezoelectric coefficient of 7.7 pC/N. The findings in this study could provide insight to future research work on PVDF, advancing its development in piezoelectric applications.