We describe the fabrication of highly sensitive graphene based field effect transistor (FET) biosensors with a cost-effective approach and their application in label-free Deoxyribonucleic acid (DNA) detection. Chemical vapor deposition (CVD) grown graphene layers were used to achieve mass production of FET devices via conventional photolithographic patterning. Non-covalent functionalization of the graphene layer with 1-Pyrenebutanoic acid succinimidyl ester ensures high conductivity and sensitivity of the FET device. The present device could reach a detection limit as low as 3 x 10(-9) M.