This study explores the gender wage gap in Türkiye between 2013 and 2022 using a novel 10-year panel dataset constructed with administrative data compiled for the first time in Türkiye, which includes approximately 14 million full-year workers in 360 subgroups by demographic, sectoral, and occupational factors. The analysis examines the long-term effects of demographic factors, such as age, education, and marital status, as well as the work-related factors, including occupation and employment sector, on the gender wage gap. The findings reveal that men working full-time in formal employment earn 10.1% more than women in Türkiye, and the study shows evidence of how the gender wage gap varies across different demographic groups. The results obtained emphasise the significant roles of marital status, occupation, age, and sector in explaining the wage differential, while education is shown not have a meaningful long-term impact on the wage gap. Moreover, contrary to expectations, the study confirms that occupational experience, the aging labour force, and increased female labour force participation contribute to the widening of the gender wage gap. These findings underline the need for targeted economic and social policies to address gender-based wage differences in a country where the labour force participation of women has traditionally been outstandingly low. This study aims to contribute to the literature by providing a comprehensive analysis of a large-scale dataset that offers new insights into gender wage differences.