This paper employs the tight-binding model to investigate the thermal properties of tetragonal Germanene (T-Ge) affected by external fields and doping. T-Ge is a two-dimensional material with unique electronic properties, including zero band gap and two Dirac points. The electronic properties of T-Ge can be influenced by bias voltage, which can open its band gap and convert it to a semiconductor due to its buckling structure. The tunable band gap of biased T-Ge, makes it a a promising option for electronic and optoelectronic devices. The band structure of T-Ge is split by the magnetic field, leading to an increases its band edges due to the Zeeman Effect. The findings demonstrate that the thermoelectric properties of T-Ge are highly sensitive to external parameters and modifications of the band structure. The thermal and electrical conductivity of T-Ge increase with increasing temperature due to the rise in thermal energy of charge carriers. The thermoelectric properties of T-Ge decrease with bias voltage due to band gap opening, increase with the magnetic field due to a modifications of the band structure, and increase with chemical potential due to increasing density of charge carriers. By manipulating the band structure of T-Ge through bias voltage and chemical doping, the electrical conductivity can be optimized to achieve higher figure of merit (ZT) and improved thermoelectric performance. The results demonstrate the potential of T-Ge for use in electronic and magnetic devices, opening up new possibilities for further research and development in this field.