Food proteins, essential ingredients in food products, extend product structuring and health-promoting benefits. The objective of the current study is to improve the bio- and techno-functionalities of food proteins simultaneously through non-thermal plasma exposure. Four different food proteins (pea, rice, wheat gluten, and milk proteins) were exposed to plasma at voltage 240V, frequency 1.5 kHz, and 30 min exposure time. The structural, digestibility, bioactivity, and techno-functional properties were analyzed. Plasma treatment alters the secondary structure of proteins by increasing β-structures and random coils by 3-4 times while decreasing α-helices by half, reducing surface hydrophobicity. The study found that longer treatment times and higher voltage intensities enhance protein digestibility and increase amino acid release, with gluten showing the highest improvement in both digestibility and free amino acid content among the proteins examined. The proteins also showed a loss of radical scavenging capacity after treatment due to oxidation reactions. Cold plasma treatment improved protein solubility but reduced emulsifying and foaming properties. The enhancements in digestibility and bioactivity can be attributed to structural unfolding and the exposure of reactive sites on the proteins. In summary, the effects of cold plasma treatment depend on the specific protein, treatment parameters, and the degree of oxidation.