This paper introduces the concept of “generative AI crafting” which captures employees’ proactive use of generative AI to automate or augment their job demands and job resources. By using open-ended surveys and web-scraped data, study 1 uncovers how employees proactively adopt generative AI. Based on these findings, Study 2 develops a multidimensional quantitative Generative AI Crafting Scale (GAICS) and evidences its factorial validity. In Study 3, we establish the convergent validity of the GAICS by relating its sub-dimensions to generic job crafting behaviour, proactive personality, perceived ease of use, perceived usefulness, and intention to use generative AI. Study 4 reveals the criterion validity of the scale, by demonstrating its associations with in-role performance, creative performance, and work engagement. Our research offers a bottom-up, employee-centric perspective on generative AI adoption, demonstrating that proactive use of generative AI in an augmenting way not only enhances employee performance but also improves well-being. In contrast, we also found that using generative AI primarily for automation does not yield these benefits. Additionally, this study provides a methodological tool for future research to explore the antecedents and outcomes of proactive generative AI adoption in the workplace.