Considerable progress in the construction of efficient fluorescence-resonance energy transfer (FRET) systems has promoted the development of artificial energy transfer materials. However, despite recent advances, the exploration of efficient and easy strategies to fabricate novel supramolecular systems with FRET activities is still a challenge. Here, we report that a two-step FRET system was successfully achieved, driven by platinum metallacycle based host-guest interactions. The two-step FRET system is used for the preparation of a white-light-emitting diode and serves as a nanoreactor for the photosynthetic process. This work offers a strategy for the fabrication of FRET systems and opens opportunities for functional materials constructed by platinum(II) metallacycle based host-guest interactions.