Heart failure is a detrimental consequence of various cardiac diseases, with its pathological basis being the progressive interstitial fibrosis-induced cardiac remodeling. Fibroblasts mediate and activate fibrosis to generate extracellular matrix, and excessive activation leads to the accumulation of matrix proteins, ultimately resulting in pathological fibrosis and organ damage. Thyroid hormone plays a crucial role in regulating the cardiovascular system, while subclinical and overt thyroid disorders impact cardiac fibrosis through a series of pathological mechanisms. Conversely, thyroid hormone replacement therapy has been considered for safeguarding cardiac function; however, comprehensive investigations on the effects of thyroid hormones on cardiac remodeling and fibrosis are lacking. The primary objective of this review is to provide an overview of current research on thyroid hormones and their association with cardiac fibrosis.