This study examines the mechanism of the digital economy on low-carbon trade competitiveness in China’s manufacturing sector using panel data from 30 provinces from 2011 to 2022, employing dynamic panel and moderated threshold model. The findings indicate that the digital economy significantly enhances manufacturing low-carbon trade competitiveness. Although green patents contribute to the overall effect, they do not serve as the primary indirect pathway through which the digital economy impacts manufacturing low-carbon trade competitiveness. Among these patents, utility model patents demonstrate the strongest mediating effect, followed by invention patents, design patents, and green invention patents, while green utility model patents show a weaker and non-significant effect. Furthermore, the digital economy facilitates a low-carbon transition in energy consumption structures, indirectly boosting manufacturing low-carbon trade competitiveness. This study also uncovers heterogeneous moderating effects of environmental regulations: market-based and voluntary regulations positively moderate the relationship, while command-and-control regulations show non-significant moderation. Environmental regulation exhibits a ‘U-shaped’ non-linear moderating effect, transitioning from non-significant negative moderation below a threshold to significant positive moderation beyond a critical value.