Purpose: This research examines the essential competencies open university students in Thailand require to meet the demands of the sustainable smart manufacturing industry. The study addresses skills gaps in technological, green, 21st-century and future-thinking dimensions, aligning with Thailand's 4.0 strategy and the United Nations Sustainable Development Goals. Design/methodology/approach: A mixed-methods approach was employed, integrating quantitative data from a survey of 421 undergraduate students, selected through stratified sampling and qualitative insights from 31 industry experts, chosen using purposive sampling. Competency assessments were validated using a four-dimensional model and analysed through descriptive statistics to compare expert expectations with student self-assessments. Findings: The study identified significant discrepancies between expert expectations and student self-assessments, particularly in advanced technological skills (e.g. robotics and Internet of Things [IoT]) and green competencies (e.g. lifecycle assessment). While students demonstrated moderate proficiency in 21st-century and interpersonal skills, comprehensive curriculum adjustments are required to address these critical gaps. Practical implications: The findings highlight the need for curriculum reforms integrating blended learning, hands-on practical training and academic-industry collaboration. These measures are critical for equipping students with the skills required for sustainable smart manufacturing. Originality/value: This study offers a validated, multi-dimensional competency framework tailored to the sustainable smart manufacturing industry. It provides actionable insights for educators and policymakers to bridge educational and industrial gaps and ensure workforce readiness for an evolving technological landscape.