A novel localization technique for frequency-domain chipless RF identification (RFID) tag is proposed. A short-duration ultra-wideband impulse radio signal interrogates the tags, and multiple receivers in the interrogation zone capture the backscattered signal from the tags. The received signals from the chipless tags are analyzed for the structural mode radar cross section to determine the relative ranges. Using the range information, the linear least square (LLS) method is employed for accurate localization of tagged items. The accuracy of the localization method is analyzed by moving the chipless tag within a fixed interrogation zone. The whole system is modeled in CST Microwave Studio Suite 2012 to comply with a realistic scenario. The post-processing for range and tag position estimation through LLS is done in MATLAB. The method is also verified in laboratory environment with fabricated chipless RFID tags and multiple receiving units. The range and angular resolution are 2.1 cm and 3.5 °, respectively. The analysis and results create a strong foundation for chipless RFID tags to be used in tracking and localization.