Tobacco smoking is a significant global public health challenge, responsible for 8 million deaths annually. This study aimed to analyze the age of smoking initiation and its sociodemographic determinants among Iranian adults, based on data from the 2021 STEPwise approach to surveillance (STEPS) survey, to inform targeted public health interventions. The analysis of 27,874 adults revealed that the average initiation ages for cigarette and hookah smoking were 22.2 years and 24.9 years, respectively. Men typically began smoking earlier than women, with average ages of 21.9 years for males and 27.7 years for females. No significant differences were observed in smoking initiation ages between rural and urban areas. Education level and marital status were also influential, with the youngest initiators having 7-12 years of education and being single. This study highlights the significant roles of gender, education, and urban-rural differences in smoking initiation in Iran. The findings underscore the need for targeted public health strategies conforming to the WHO's MPOWER initiatives and the Framework Convention on Tobacco Control (FCTC). Increased investment in public health, focusing on education and preventive measures, is crucial to reduce early smoking initiation and its associated health risks, ultimately supporting broader health policy goals.