Epidermal growth factor receptor (EGFR) homodimers and heterodimers play significant roles in a variety of tumors, but current imaging probes remain problematic due to restricted contrast and sensitivity. Thus, we have developed aptamer-mediated activated conformational transitions to target the EGFR and HER2. Furthermore, based on signal amplification techniques, especially the FRET fluorescence enhancement properties of poly-β-CD, supramolecular FRET signal amplification nanoprobes were constructed to improve imaging contrast and sensitivity. The results confirmed that the fluorescence intensity of the supramolecular FRET group probe is 1.2 to 1.3 times that of the multi-FRET group and 11.3 to 23.2 times that of the single-FRET group. The results further confirmed that the supramolecular nanoprobe could not only be activated by tumor cells and tissues to achieve high-contrast imaging of EGFR/EGFR and EGFR/HER2 dimers, but also successfully distinguish tumor cells and tissues from normal cells and tissues. The strategy provides a generalized platform for high-contrast imaging of other dimers intending to deepen the understanding of the central roles of multiple dimers in cancer development.