In this study, we examined the highly selective sensing of Fe3+ ions in water using metal complex-functionalized mesoporous silica materials. Metal complex-functionalized mesoporous silica materials were synthesized on the mesoporous surface of SBA-15 via complexation process between Eu3+ and aminosilane groups. Mesoporous silica, SBA-15, and the Eu3+-complex functionalized SBA-15 were characterized using X-ray diffraction (XRD), transmittance electron microscopy (TEM), nitrogen sorption behavior, and Fourier transform infrared (FTIR) spectroscopy. The sensing behavior of the Eu3+-complex functionalized SBA-15 was studied using various metal ions (Fe3+, Cu2+, Cr3+, Co2+, Hg2+, Pb2+, and Zn2+) aqueous solutions. Photoluminescence intensity (λ = 612 nm) of the Eu3+-complex functionalized SBA-15 was dependent on the different interactions between metal ions and Eu3+-complexes. Photoluminescence intensity at λ = 612 nm of the Eu3+-complex functionalized SBA-15 decreased to near zero and proved the highly selective sensing effect of Fe3+. Therefore, the Eu3+-complex functionalized SBA-15 can be considered an excellent candidate for sensing iron ions in water.