Synergistic Digitalization and Greening for Corporate Total Factor Productivity Growth: Evidence from Chinese A-Share Firms

China’s dual pursuit of a “Digital China” and its carbon-neutral goals has driven a coordinated strategy of digitalization and green transformation. Yet the extent to which firms have realized this synergy—and its effect on total factor productivity (TFP)—remains underexplored. Using panel data from 2011 to 2025 on all A-share listed companies, we construct a composite index of digital–green coordination and estimate firm-level TFP via the Levinsohn–Petrin method. Employing fixed-effects panel regressions and mediation analyses, we find the following: (1) the digital–green synergy significantly enhances TFP growth, with robustness confirmed across alternative measures, propensity score matching, city fixed effects, and instrumental variable approaches; (2) this effect is stronger for non-SOEs and firms with higher baseline TFP and exhibited an “inverted-U” pattern over China’s 13th and 14th Five-Year Plans; (3) corporate social responsibility (CSR), cost stickiness reduction, and green technological innovation each mediate this relationship—CSR and cost stickiness play larger roles in SOEs, while green innovation mediates across all firm types and TFP levels, also showing an “inverted-U” temporal trend; and (4) over time, CSR’s mediating effect wanes in the 14th Five-Year period, cost stickiness mediation gradually declines, and green innovation mediation is continually strengthened. These findings provide evidence of the association between digital–green alignment and firm productivity in China, using an index that summarizes the joint orientation toward digitalization and greening.