Plant-based protein sources impart grassy off-flavors, when used in bland-tasting products like dairy alternatives, reducing their consumer acceptability. This study aimed at improving the aroma of pea protein isolates (PPI) using lactic acid fermentation (LAF) hypothesizing that LAF could mask undesirable aroma from pea protein. LAF treatments were performed by using Lactobacillus plantarum. Solid-phase microextraction followed by gas chromatography-mass spectrometry (SPME-GC-MS) was used to compare the volatile profile of plant-based protein undergoing LAF treatment. Evolution of functional properties including emulsifying properties, foaming properties, water holding and oil binding capacities of samples, Bradford protein content and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) profile, were analyzed. Based on the experimental results, water-soluble protein content decreased with increase of fermentation time, and protein configuration was changed, starting from 15-h of fermentation. A 10-h L. plantarum fermentation was found optimal in eliminating off-flavour while maintaining protein functionality. Around 42% aldehyde and 64% ketone content were removed, and a small amount of alcohol was produced. This change in aroma profile was considered desirable for PPI products, which would be used for yogurt substitute production. A descriptive analysis sensory test was performed, and the result showed that LAF treatment improved the PPI aroma and taste. •Lactic acid fermentation of pea protein was developed to reduce off-flavours.•Fermentation resulted in the break-down of larger peptides, resulting in lower protein solubility.•Fermentation increased alcohol volatiles and decreased aldehyde volatiles.•A fermentation time of 10–15 h was found optimal for lactic acid fermentation.•LAF treatment improved the taste of pea proteins based on descriptive sensory analysis.