Nickel nanoparticle (NiNPs)-doped carbon nanofiber (CNF) grafted with Rhodamine-B (RhB) dye (Ni- CNF-RhB), was prepared and utilized as a colorimetric probe for detection and measurements of chromium (Cr3+) and lead (Pb2+) metal ions in aqueous systems. An intense pink solution was obtained within 30 s on the exposure of the colorless Ni-CNF-RhB probe to the metal ions (Cr3+ and Pb2+) solution. Briefly, the NiNPs-doped carbon beads were synthesized and applied as a substrate to grow CNFs by chemical vapor deposition. The Ni-CNF-RhB colorimetric probe exhibited fast response and selective determination towards Cr3+ and Pb2+ over the 0.1-10 ppm concentration range of their respective solution pH. The developed probe also showed the pH-dependent colorimetric response, thereby, selectivity determination of the metal ions. The detection limits of the colorimetric probe against Cr3+ and Pb2+ are 203 and 132 nM, respectively. The binding ability of the RhB-dye was augmented by CNF and NiNPs, while the carbon beads provided support to CNF to help probe in detection application and its re-usability. The method to prepare the colorimetric probe is simple, novel, selective, and the probe can be efficiently used for the fast detection (naked eye) and measurements of toxic metal ions in aqueous systems.