The phytohormone ABA was known to play a vital role in modulating plant responses to drought stress, and AtMYC2 (a GhbHLH1 homolog) had been proved to act as transcriptional activator involved in the dehydration and ABA response pathway in Arabidopsis. Here, using AtMYC2 amino acid sequence as a querying probe to screen Gossypium hirsutum L. EST database and contigging the candidate ESTs, the putative full-length cDNA sequence of cotton bHLH transcription factor was assembled and confirmed by amplifying leaves cDNA of drought-treated upland cotton cv Jinmian 19. The full-length cDNA named as GhbHLH1 has an open-reading frame of 2,025 bp, encoding a protein of 674 amino acids with a calculated molecular mass of 73.6 kDa and an isoelectric point of 5.46. Sequence alignment shows that GhbHLH1 contains a 60 amino acid long bHLH domain and have high homology with bHLH domain proteins in Arabidopsis, especially with AtMYC2, which plays an important role in response to stress stimuli. Semi-quantitative RT-PCR reveals that GhbHLH1 is strongly expressed in 7-day- post anthesis fibers but weak in roots, stems, and leaves. Based on real-time quantitative RT-PCR, the expression of GhbHLH1 in leaves was transitorily induced by ABA and PEG treatments, although its transcripts were accumulated in various organs. However, its expression was not affected by salt and cold treatments. Our results may provide the basis for future research of bHLH domain gene’s roles as a regulator of ABA signaling in cotton.