A miniaturized Bagley Polygon power divider based on composite right/left-handed transmission line is presented. The composite right/left-handed transmission line and conventional microstrip transmission line are utilized to realize the 0° phase shift transmission line, which is used to replace the 180° transmission line of the conventional Bagley Polygon power divider. As a result, miniaturization is realized, without deteriorating the isolation between the output ports. The design equations are presented. This power divider shows advantages compared with other miniaturized ones. For verification, a miniaturized Bagley Polygon power divider is designed and fabricated. The 58.2% length reduction of the counterpart is realized. The measurement and simulation results show good agreement.