Solar thermal collectors (STCs) are a potential heating and cooling solution owing to their pollution-free nature and availability in many parts of the globe. Enhancing the thermal efficiency of STCs is crucial for optimizing energy conversion. In this respect, the purpose of this article is to provide an overview of the usage of carbon nanotubes (CNTs) for the enhancement of thermal performance in evacuated tube and flat plate solar thermal collectors. According to the research that was conducted earlier, it was discovered that the use of CNTs, both single-walled and multi-walled, results to increases the efficiency of a flat and evacuated solar thermal collector. In this article, the impact of carbon nanotubes (CNTs) was investigated in depth for their potential usage in flat and evacuated tube solar collectors (ETSCs). This review article offers a novel aspect based on extensive research that has been published in the past related to the impact of CNTs on the thermal performance of flat and ESTCs.