Pleurolus eryngii loaded Fe2O3 magnetic nanoparticles were developed as novel magnetic solid phase bio-extractors for the preconcentrations and extractions of Co(II) and Hg(II) from real samples. The metal binding surface groups of the prepared magnetic solid phase bio-extractors were investigated by FT-IR spectrometry, SEM and EDX. Several parameters influencing the magnetic extractions and preconcentrations of Co(II) and Hg (II) were examined and optimized, including pH, flow rate, quantity of P. eryngii, quantity of Fe2O3 magnetic nanoparticle, eluent type, concentration and volume, sample volume, and foreign ions. A good reusage (35 times) was obtained with the relative standard deviation (RSD) of < 5.0% for both magnetic solid phase bio-extractors. The biosorption capacities were determined for Co(II) and Hg(II) as 25.4 mg g(-1) and 30.3 mg g(-1), respectively, using P. eryngii loaded Fe2O3 magnetic nanoparticle column. The preconcentration factors for Co(II) and Hg(II) were found as 80 and 100, respectively, when using P. eryngii loaded Fe2O3 magnetic nanoparticle column. The developed procedures were validated through analysis of the certified reference materials and successfully utilized for the determinations of Co(II) and Hg(II) in real samples by inductively coupled plasma optical emission spectrometry (ICP-OES) with satisfactory results.