Improving land use performance in specialty agriculture is key to building a strong agricultural nation under resource and environmental constraints. Based on panel data from 288 prefecture-level cities in China from 2010 to 2022, this study employs a fixed-effects model to examine the impact and underlying mechanisms of the synergy between industrial chain extension and functional chain expansion on land use performance in specialty agriculture. The findings indicate that this synergy significantly enhances land use performance, primarily by improving land use benefit. The mechanism analysis reveals that the synergy between industrial chain extension and functional chain expansion can enhance land use performance by strengthening the market competitiveness of specialty agriculture products and promoting the industrial agglomeration of specialty agriculture. Moreover, the heterogeneity analysis shows that this synergy has a “supporting the weak” effect in regions with acquired resources, while exhibiting a “resource boon” effect in regions with abundant inherent distinctive resources.