The authors synthesised porous GdF:Er,Yb-COOH core-shell structured bi-functional nanoparticles through a one-step hydrothermal route during which ethylene diamine tetraacetic acid) was bound to the surface of the nanoparticles. It has high up-conversion emission intensity for monitoring the drug release process and magnetisation saturation value (10.2 emu/g) for drug targeting under foreign magnetic fields. Moreover, porous GdF:Er,Yb as drug carriers with a high drug-loading efficiency. cis-Dichlorodiammineplatinum(II) (cisplatin, CDDP)-loaded GdF:Er,Yb nanoparticles (GdF:Er,Yb-CDDP) were characterised by the Fourier transform infrared spectra, and CDDP was loaded in the form of electrostatic interaction and hydrogen bonds. Compared with CDDP alone, GdF:Er,Yb-CDDP nanoparticles increase concentration of CDDP in the target site and enhance its anticancer efficiency. Therefore, the as-prepared GdF:Er,Yb-COOH nanoparticles allow simultaneous targeted drug delivery and monitoring as promising anti-cancer theranostic agents.