<p>With the rapid development of the marine economy, land use in coastal urban areas has exhibited significant spatial complexity that increases with changes in population and economic‒industrial structures. To quantify urban complexity and its relationship with economic and demographic factors, this study analyses the fractal characteristics of coastal settlement patterns in Xiamen, China, and their correlations with GDP and population. The results show that the fractal dimension of settlement land-use patterns follows a nonlinear trend over time. Projections indicate that outside Xiamen Island, the fractal dimension will decline to a critical threshold of 1 by 2028, emphasizing the urgency of land-use conservation. Additionally, a negative correlation is observed between the fractal dimension and both the regional GDP and the resident population on and off Xiamen Island. Correlation analysis suggests that areas outside the island with higher fractal dimensions may have greater potential for GDP growth and population expansion compared to the island itself. This study provides insights into the fractal mechanisms of coastal settlements and supports the optimization of land-use control strategies. By quantifying small-scale and dynamic characteristics of fractal landscapes, this study provides decision-making support for spatial planning and resource allocation in coastal regions and represents a valuable contribution to urban geography.</p>