The KEAP1–NRF2–ARE pathway is the master regulator of antioxidant and cytoprotective responses to oxidative and electrophilic stress. The KEAP1–NRF2 interaction can be disrupted by direct interference with the protein–protein interface or by covalent modification of cysteine residues at the “sensor” region of KEAP1. A number of biophysical methods are useful to characterize the KEAP1–NRF2 protein–protein interaction, including fluorescence polarization, fluorescence correlation spectroscopy, Förster resonance energy transfer, thermal shift assay, isothermal titration calorimetry, surface plasmon resonance, biolayer interferometry, analytical ultracentrifugation, electrophoretic mobility shift assay, circular dichroism, saturation transfer difference NMR experiments, and X-ray crystallography. On the other hand, considering that NRF2 is a master regulator of many cytoprotective genes and represents a cross talk of numerous key signaling pathways, the biological evaluation of potential NRF2 activators generally comprises their ability to promote NRF2 activation and translocation to the nucleus and also the levels of expression of NRF2-controlled proteins and the mechanism by which NRF2 is activated. A number of biological techniques are employed for this purpose, including immunocytochemistry and immunohistochemistry, the study of gene reporter cell lines, and the activation and expression of key genes and proteins, as well as the use of knockdown/knockout cell and animal models. Regarding mechanistic studies, covalent bonding to KEAP1 can be established by KEAP1 isolation through immunoprecipitation followed by mass spectrometry or HPLC/UPLC. FRET-based techniques and the proximity ligation assay allow to assess whether the KEAP1–NRF2 interaction is disrupted by a particular compound.