This study aims at a crystallization process of metallic glass ribbon. An impact of the magnetic interaction upon the crystallization process is reported. Amorphous ribbon composed of Fe76 Mo8 Cu1 B15 has been covered by sputtered Co layer in the range 0–100 nm. Deposited Co layers were investigated by magneto-optical Kerr measurements which confirm their ferromagnetic character. The amorphous ribbons with and without Co cover layer were thermally treated under the elevated temperature. Afterwards, the degree of crystallization was determined using transmission Mössbauer spectroscopy and conversion electron Mössbauer spectroscopy measurements at room temperature. Sputtered cobalt layer significantly boosts development of nanograins in the whole amorphous matrix. It was revealed that the crystallization enhancement was caused by magnetic impingement of ferromagnetic Co layer with the thickness higher than 30 nm.