In the last few decades, extensive research has been focused on the ever-increasing demand for energy-efficient materials and technologies in consumer electronics. The low-weight, low-cost, environmentally safe Li-based ceramics are widely investigated as potential materials for Li-ion batteries and low-temperature cofired ceramics (LTCC). In the present work, we combine high volume fractions of Li2TiO3 (LT) ceramic with incredibly versatile polytetrafluoroethylene (PTFE) to synthesize thermally stable, low-loss dielectrics at ultralow temperatures (<150 °C) in a single step without any additional transient liquid phase in a very short time, and the effect of different wt % of ethylenediaminetetraacetic acid (EDTA), which is a chelating agent, on the densification, microstructure, thermal, and broadband dielectric properties of these composites has been studied. X-ray photoelectron and FTIR spectroscopic analyses were used to explain the densification mechanism in these composites. The presence of the OH– ion on the surface of LT and manipulation of the ceramic-polymer interphase by EDTA are significant in the densification of LT-PTFE composites. A cylindrical prototype dielectric resonator antenna (CDRA) was designed, simulated, and fabricated with the 0.7LT-0.3PTFE-5EDTA composite having excellent thermal and dielectric properties, and antenna properties were experimentally verified. The return loss, input impedance, and radiation pattern of the CDRA were examined, and the experimental results match reasonably well with simulated results. This study shows that the 0.7LT-0.3PTFE-5EDTA composite is a potential candidate for the fabrication of an economical, low-loss, lightweight, easy-to-fabricate, wide bandwidth CDRA for telecommunication applications in the Ku-band. Further, it is possible to achieve enhanced bandwidth and gain, by varying the compositions of these composites.