Epithelial-mesenchymal transition (EMT) is recognised as a crucial embryonic process that converts immotile epithelial cells into migratory mesenchymal cells. More recently, EMT has been implicated in key stages of tumour progression, whereby it facilitates epithelial cancer cell metastasis. Traditionally, molecular and cell biology-based approaches have been utilised to study EMT. However, a recent wave of EMT research has implemented proteomic techniques to reveal new insights, and these integrated strategies have implicated novel proteins in the process of EMT. In this review, we highlight the important contributions proteomics has made in broadening our existing knowledge of EMT. Recent advances in sub-proteome sample preparation, proteomic tools including mass spectrometry instrumentation and protein quantitation, will further refine and extend our understanding of the cellular EMT process.