A novel chemiluminescence resonance energy transfer (CRET) system was developed and combined with a structureswitching aptamer for the highly sensitive detection of platinum. Platinum was chosen as a model analyte to demonstrate the generality of the new CRET system. This aptameric platform consisted of a streptavidin labeled aptamer against platinum and a streptavidin-coated magnetic bead for the selective separation of platinum-bound aptamer. The platinum-aptamer probe contained several guanine (G) bases bound to the 3,4,5-trimethoxyphenylglyoxal (TMPG) donor group at the 5′ end, a fluorescent acceptor (6-carboxy-2′,4,7,7′-tetrachlorofluorescein, TET) at the 3′ end, and a streptavidin aptamer sequence in which several base pairs were replaced by the G-G mismatch to induce the platinum-oligonucleotide coordination. The chemiluminescence (CL) generated by TMPG/G bases is transferred to the acceptor (TET). In the presence of platinum, the platinum-aptamer probe was folded such that the G bases at the 5′ end and TET at the 3′ were in close proximity. The complex was separated using streptavidincoated magnetic beads by the addition of TMPG to form the TMPG/G bases complex. The ultraweak CL from the TMPG/G bases was strongly enhanced by TET. This novel CRET-based method can be easily performed with high limit of detection (50 ng•mL −1 ) and selectivity over other metal ions. This technique provides a novel method for simple, fast, and convenient point-of-care diagnostics for monitoring proteins and metal ions.