Red emitting europium (III) complexes Eu(TFAAN)₃(P(Oct)₃)₃ (TFAAN = 2-(4,4,4-Trifluoroacetoacetyl)naphthalene, P(Oct)₃ = trioctylphosphine) chelated on carboxymethyl dextran coated superparamagnetic iron oxide nanoparticles (CMD-SPIONs) was synthesized and the step wise synthetic process was reported. All the excitation spectra of distinctive photoluminesces were originated from f-f transition of EuIII with a strong red emission. The emission peaks are due to the hypersensitive transition ⁵D₀→⁷F₂ at 621 nm and ⁵D₀→⁷F₁ at 597 nm, ⁵D₀→⁷F₀ at 584 nm. No significant change in PL properties due to addition of CMD-SPIONs was observed. The cytotoxic effects of different concentrations and incubation times of Eu(TFAAN)₃(P(Oct)₃)₃ chelated CMD-SPIONs were evaluated in HEK293T and HepG2 cells using the WST assay. The results imply that Eu(TFAAN)₃(P(Oct)₃)₃ chelated CMD-SPIONs are not affecting the cell viability without altering the apoptosis and necrosis in the range of 10 to 240 μg/mL concentrations.