As generative AI is increasingly adopted, expectations for productivity gains are rising, and its applications across business domains are rapidly expanding. However, only a few studies have empirically examined generative AI from the employee perspective. A major barrier to its adoption is the fear that employees may be replaced by AI, highlighting the need for evidence-based strategies to enhance employee motivation. This study investigated how business service concepts related to generative AI influence employee motivation through a randomized controlled trial involving 1,000 non-managerial employees in the Japanese consumer goods manufacturing sector. Participants were randomly assigned to a control group that emphasized productivity or to one of four treatment groups, each highlighting a different concept: creativity, skill growth, work-life balance, or autonomy. The results revealed that only work-life balance—specifically, the idea of ‘leaving work on time’ due to reduced routine tasks by AI—significantly increased motivation compared to the control group (p = 0.007). These findings suggest that messages aligned with employees’ values and concerns are more motivating than appeals based solely on managerial rationales such as efficiency or cost reduction. Thus, introducing generative AI should not be approached merely as a matter of technological innovation or management strategy, but as a communication challenge centred on employee engagement. Embedding values such as ‘time’, ‘quality of life’, and ‘well-being’ into the core of business service concepts is essential for driving successful transformation.