In recent years, generative artificial intelligence (generative AI) has become increasingly embedded in organizational activities, reshaping employees’ task execution, job design, and work experiences. As employees increasingly collaborate with generative AI, such collaboration extends beyond simple tool use and takes the form of an ongoing partnership that fundamentally alters how tasks are structured and experienced. To capture this emerging form of work, this research develops and validates a multidimensional scale of employee–generative AI collaboration characteristics. Conceptualizing tasks and technology as an integrated whole, we focus on key task-level characteristics that reflect how such collaboration is experienced by employees. The final 24-item scale measures five characteristics of employee–generative AI collaboration: collaborative skill variety, collaborative task significance, collaborative task autonomy, collaborative emotional interaction, collaborative responsibility clarity, contributing to the development of knowledge in the rapidly growing literature on employee–generative AI collaboration. The scale enables the systematic examination of individual differences in task experiences under employee–generative AI collaboration and advances work design theory by providing a tool to investigate how task characteristics are shaped when task execution is distributed across employees and generative AI.