Introduction: Google Sites was chosen because it can provide real-time services when there are updates to learning materials.Objective: This research aims to develop mobile learning based on Google Sites and determine its effect in improving the skills of 21st-century vocational students.Methods: The development model is based on the Research and Development models by Gall, Gall, and Borg. Product validation by experts is getting a very proper predicate. The application of the media was conducted for students in the 11th class of the Machining Engineering Competency. The product was tested in three Vocational High Schools (VHS) with 78 respondents in three practical and three control classes. The data collection techniques utilized in this study encompassed a multiple-choice test of 4C abilities; an observation sheet completed by teachers, and structured interview instruments for both students and teachers. Data analysis techniques include: (1) qualitative data analysis employing an interactive approach involving data reduction, data display, and conclusion drawing; and (2) quantitative data analysis comprising tests for normality, homogeneity, and hypothesis testing using the independent sample t-test.Results: Findings of the research indicated that: (1) observations conducted by teachers revealed a significant enhancement in skills within both experimental and control groups; (2) within the experimental group, critical thinking skills increased by 11, 85%, communication skills by 5.6%, collaboration skills by 11, 72%, and creative skills by 8%; and (3) the results of the t-test can be inferred that there exist notable disparities between the practical and control classes across the three schools.Conclusions: The conclusion drawn from this research is that Google Sites-based mobile learning effectively enhances the 21st-century skills of students in Vocational High Schools