The yellow-feather broiler is a popular poultry breed in Asia, particularly in China. In this study, we performed RNA-seq analysis to identify differentially expressed genes (DEGs) in the heart of yellow-feather broilers that had been subjected to heat stress treatment (38 ± 1 C for 8 h, over 7 d) and determine the response of the heart to high temperature and its effects on yellowfeather broiler physiology. We found that body weight (BW) of the heat stress treatment group (BW 28 ¼ 354.8 ± 34.8 g) was significantly decreased (p ¼ .033) compared with that of the control group (BW 28 ¼ 384.8 ± 58.9 g). However, there was no significant reduction in the heart relative weight (HRW) (p ¼ .538). A total of 37 DEGs related to energy metabolism responded to heat stress in the heart of yellow-feather broiler. The results of KEGG pathways analysis indicated that these genes are involved in oxidative phosphorylation (KO: 00190), cardiac muscle contraction (KO: 04260) and carbon metabolism (KO: 01200). Analysis of the cardiac transcriptome of yellowfeather broilers subjected to heat stress indicated that the heart of these birds has specific physiological mechanisms for regulating body growth in response to high-temperature environments. HIGHLIGHTS Yellow-feather broilers, a popular poultry breed in Asia, were used to determine how the heart responds to heat stress. A total of 37 genes in the heart of yellow-feather broilers showed differential expression in response to heat stress. The differentially expressed genes (DEGs) are associated with oxidative phosphorylation, cardiac muscle contraction and carbon metabolism pathways.