The rapid evolution of artificial intelligence (AI) has profoundly reconfigured the contemporary workplace, redefining the interactions among human employees, AI systems, and organizational processes. Yet, most research adopts a tool-centric view, overlooking how AI’s emergence as an alternative working agent reshapes managerial attention and employee welfare. Drawing on the attention-based view (ABV) and a dual-agent model, we theorize that AI adoption activates two opposing mechanisms: a human attention gain mechanism, where collaboration needs heightened focus on employees and increased employee-related corporate social responsibility (ECSR), and an AI attention shift mechanism, where deep AI embedding redirects attention toward AI, suppressing ECSR. Using panel data from 2575 Chinese listed firms (2013–2023), we find an inverted U-shaped relationship between AI adoption and ECSR. Moreover, industry AI substitution risk sharpens and left-shifts this curve, while top management team (TMT) functional diversity and employee stock ownership flattens and right-shifts it. These findings advance research on AI adoption, managerial attention, and employee-focused CSR by illuminating how attention allocation in dual-agent contexts shapes ethical and strategic outcomes, offering actionable insights for balancing human–AI integration with sustained employee welfare.