This paper presents 21st Century Skills that are ideal for Vocational High Schools (SMK) in Indonesia using library research methods or approaches. Data collection is carried out by studying, exploring a number of books, documents and journals (both in printed and electronic form) as well as other sources of data and / or other information that relevant to research or studies. The aim is to define 21st Century Skills that are ideal for Vocational High Schools (SMK) in Indonesia. Seeing the various urgencies of SMKs in facing the era of the industrial revolution 4.0 which is developing at this time, it is very necessary to support the development of soft skills that need to be provided for vocational students. Hence, ideal soft skills are needed to help the development of SMK in the future. The result in general soft skills that are predicted to be able to answer the guidance of modernization are 21st Century skills, specifically the 21st Century skills that are closest to the aim of Vocational High Schools and Vocational Education in Indonesia are Life Career Skills. The development of hard skills can be known through the results and real processes of working to train students' tactical and technical abilities, while the development of soft skills is needed in order to make children be able to be professional and develop to complete all the work they do.