Abstract: The ethylene response factor (ERF) transcription factor family plays a crucial role in plant growth and development, secondary metabolite synthesis, and adaptive responses to biotic and abiotic stressors. This study characterized the McERF003 transcription factor from Michelia crassipes Law. to elucidate its regulatory role in phenylpropanoid metabolism and high-temperature stress resistance. The full-length sequence of McERF003 was cloned from the perianth tissue and analyzed through bioinformatic approaches. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to assess expression patterns across multiple tissues and under different abiotic stress conditions. An McERF003 overexpression construct was generated and transformed into tobacco (Nicotiana tabacum L.) for functional validation. Results showed that McERF003 encoded a 183-amino-acid protein with an isoelectric point of 9.10 and a molecular weight of 20 286.04 Da. Expression profiling revealed predominant transcription in roots and significant differential induction under high-temperature, low-temperature, and salt stress conditions. Transgenic tobacco plants exhibited no notable differences in flower color or anthocyanin content relative to wild type, but displayed elevated flavonoid and lignin content in both corolla and leaves. Following exposure to heat stress, transgenic plants exhibited reduced wilting, low relative electrolyte leakage, and decreased malondialdehyde accumulation. Moreover, soluble protein, proline, flavonoid, and lignin concentrations were higher in transgenic plants, accompanied by significantly enhanced superoxide dismutase, peroxidase, and catalase activities. These findings demonstrate that McERF003 overexpression promotes the synthesis of phenylpropanoid metabolites and confers enhanced high-temperature resistance in tobacco, revealing its potential role in improving stress resilience through metabolic regulation.