The industrial chain digitization (ICD) is a crucial driving force for improving energy efficiency and achieving sustainable development. Based on China’s 2002–2017 input–output table, this paper used the structural path analysis method to construct the ICD panel data. We employed the two-way fixed effects model to explore the impact of ICD on demand-side energy intensity. The research findings are as follows: (1) The ICD can significantly reduce energy intensity. The results were robust after some endogeneity tests. (2) There is heterogeneity between digital manufacturing and service inputs. China’s ICD mainly relies on the automation and intelligence of production equipment to achieve energy-saving. (3) The sectoral digital intermediate input, the intelligence level, and the industrial chain energy flow have a positive moderating effect on the energy-saving effect of ICD. (4) The ICD can reduce energy intensity by improving labor productivity, strengthening the industrial chain synergistic division ability, accelerating intelligent transformation, and promoting technological innovation. This paper provided targeted policy recommendations to promote the ICD level and achieve energy-saving and emission-reduction targets based on the research results.