In the present study, a fluorescent optosensor containing a molecularly imprinted polymer in combination with electrospinning was employed for selective recognition of 2,4-dichlorophenoxyacetic acid (2,4-D). Free radical polymerization was carried out on the surface of polyethersulfone (PES) nanofibers as a substrate using a monomer, initiator, template and a polymerizable 1,8-naphthalimide derivative as the fluorogenic monomer. PES nanofiber@fluorescent molecularly imprinted polymer (PES nanofiber@FMIP) was produced by means of UV curing. The magnetic PES nanofiber@FMIP was developed in the same manner as the magnetic Fe3O4 nanoparticles were exerted in the electrospinning of the PES nanofiber. The imprinting factor (IF) was considered 1.97 as a selective character of PES nanofiber@FMIP versus PES nanofiber@FNIP. The developed sensor was able to selectively determine 2,4-D in a linear range of 1 x 10(-7)-1 x 10(-3) M with limit of detection (LOD) of 1.01 x 10(-8) M. The results confirmed that PES nanofiber@FMIP was satisfactorily able to determine trace concentrations of 2,4-D.