How Vietnamese Gen Z Knowledge Workers Use ChatGPT to Enhance Productivity and Job Performance?

The contemporary global economy is undergoing a profound structural transformation driven by the rapid deployment of generative artificial intelligence (AI). Against the backdrop of Vietnam's aggressive national strategy for digital transformation, this study critically analyzes the multifaceted relationship between ChatGPT utilization and workplace productivity among Generation Z knowledge workers. By extending the Unified Theory of Acceptance and Use of Technology (UTAUT) framework, a quantitative cross-sectional research design was employed to move beyond simple binary metrics of technology adoption. Primary data was collected via an online survey from 248 young professionals operating in high-cognitive sectors, and analyzed using Exploratory Factor Analysis and Multiple Linear Regression. The empirical findings confirm that the realization of efficiency gains from generative models is not automatic, but deeply contingent upon how the technology is embedded, commanded, and trusted by the user. Specifically, Usage Intensity and Integration emerged as the most dominant predictor of Overall Job Performance, suggesting that deep workflow integration is required to significantly elevate performance outcomes. Concurrently, AI Literacy and Prompting Skills showed the strongest impact on Perceived Output Quality, demonstrating that technical capability directly determines the standard of the generated deliverables. Furthermore, Trust and Reliability Perception positively affected all dependent variables, acting as an absolute psychological prerequisite for utilizing AI to confidently enhance work efficiency. The study concludes that simply providing access to AI tools is insufficient; organizations must actively foster digital fluency, advanced prompting literacy, and systemic trust to fully empower their Generation Z workforce.