Previous studies have indicated that hormonal control is essential for plant root growth. The root of the carrot is an edible vegetable with a high nutritional value. However, molecular mechanisms underlying hormone-mediated root growth of carrot have not been illustrated. Therefore, the present study collected carrot root samples from four developmental stages, and performed transcriptome sequencing to understand the molecular functions of plant hormones in carrot root growth. A total of 160,227 transcripts were generated from our transcriptome, which were assembled into 32,716 unigenes with an average length of 1,453 bp. A total of 4,818 unigenes were found to be differentially expressed between the four developmental stages. In total, 87 hormone-related differentially expressed genes were identified, and the roles of the hormones are extensively discussed. Our results suggest that plant hormones may regulate carrot root growth in a phase-dependent manner, and these findings will provide valuable resources for future research on carrot root development.