Piezoelectric materials have excellent piezoelectric and dielectric properties for versatile device applications. However, they have brittle properties, particularly under mechanical impulse force. As a result, there have been many attempts to improve their brittle properties by mixing in elastic materials. Here, for the first time, reduced graphene oxide (rGO) was introduced to the Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PMN-PT) and poly(vinylidene fluoridetrifluoroethylene) P(VDF-TrFE) polymer composite films, and showed the highest value of piezoelectric and energy density for flexible energy generation applications. rGO has conducting properties with 2-dimensional structure. This rGO can also be prepared through easy processing. 2-dimensional structured rGO serves as a floating electrode in PMN-PT/polymer composite flexible films. Therefore, a floating electrode can attract electrons in piezoelectric composite materials so as to enhance the energy generation properties. By introducing the rGO based floating electrodes into the PMN-PT and P(VDF-TrFE) composite, the generated output energy density was increased from 0.70 mJ/cm(3) to 1.2 mJ/cm(3). This the generated output energy density was the recorded outstanding value among the flexible composite films. In this paper, the effects of rGO on the properties of PMN-PT/polymer composites will be investigated and discussed.