The present research explores the pure electronic thermoelectric (TE) potential of continuous molecularly modified p- and n-type carbon nanotube fiber (CNTF) filaments embedded within a sustainable geopolymer (GP) mortar. The intrinsic semi-conducting properties of the as-received CNTF individual filaments were stably tuned via a versatile and scalable dip-coating process immersed within purposely prepared p- and n-type water-based dopants. Then, the p- and n-doped CNTF filaments were further deployed as electrically in-series interconnected 8 p-n thermocouples for the development of a structural component with self-powered temperature sensing capacity. The obtained p-n block-like thermocouple sensitivity of │45 μV/K│ for a temperature difference (ΔT) of 50 K is corresponding to a responsive novel and energy-autonomous structural temperature sensor at system level. Remarkably, a consistent 470 % reversible fluctuation of the generated TE voltage was pointed out correlated with a temperature change of 10 K upon multiple heating-cooling cycles. The proposed multifunctional structure promisingly envisages the proper employment of CNTF filaments for sensing and energy harvesting applications in large-scale constructions for monitoring of thermal shocks during their service lifetime, contributing toward future and near zero-energy consumption infrastructures.