Protein nanofibrils (PNFs) from plant-based protein sources have great potential for use in new sustainable food applications or biobased materials. Plant-based proteins from seven different sources (fava bean, mung bean, lupin, oat, rapeseed, soybean, and potato) were evaluated here for their ability for forming PNFs and compared with whey protein PNFs. Formation of PNFs was studied under incubation at acidic conditions (pH 2) and heat (85-90 °C) for 24-96 h. Presence of PNFs was detected using thioflavin T, circular dichroism spectroscopy, Fourier-transform infrared spectroscopy, and atomic force microscopy. The results showed that all plant-based proteins were able to form PNFs. For some of the plant protein isolates in this study, nanofibril formation is reported for the first time. We also describe and compare the distinct features associated with each protein source and the morphological alterations of the nanoscale structures. Finally, we describe how PNF production can be enhanced by purifying the fibril-forming protein component. Taken together, our study suggests that the structural and functional variation within plant protein nanofibrils can be exploited in future scaled-up food or material applications.