Novel nanofibers of biodegradable polycaprolactone (P(L) modified with light-responsive azobenzene were prepared by electrospinning upon a facile one-pot reaction. The surface chemistry of the nanofibers was probed by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary Ion mass spectrometry (ToF-SIMS). Both XPS and ToF-SIMS spectra proved the successful conjugation of azobenzene with PCL. ToF-SIMS not only enabled chemical mapping but also provided morphology information, supplementary to scanning electron microscopy (SEM). The large, reversible, and light-responsive wettability changes of the functional fibrous surfaces were further demonstrated using UV-vis spectroscopy and contact angle (CA) measurements.