Fiber optic sensors (FOS) for vibration monitoring of smart structures have certain advantages over conventional strain gage based sensors due to electromagnetic environment insensitivity and high response bandwidth. During the present study, a spatially integrating fiber optic sensor was used for vibration monitoring. It is based on the concept that the optimal placement of the sensing element can be sought by using a priori knowledge of the mode shapes of the structure. The applicability of this approach to polarimetric optical fibers is described. The acquired integrating FOS signal was used to sense and control the vibration of an eleetrorheological adaptive structure subjected to a random external excitation.