Vocational school students are expected to master 2.000 up to 3.000-word levels for general communicative purposes and 4.000 to 5.000 or more word levels for academic purposes. Using students' self-regulation control could develop their motivation to achieve more word levels autonomously. Therefore, this study investigates the relationship between vocational school students' word knowledge level and self-regulation. This study accommodates 39 items of the Word Knowledge Level (WKL) test from 1,000 to 5,000-word level to examine students' word level. Meanwhile, self-regulation was tested towards five controls: commitment, metacognitive, satiation, emotion, and the environment, using a Likert scale with 16 questions. This research was conducted online with 173 participants from vocational school students in grades I oth and 1 1th in Jakarta Timur. The researcher used the WKL formula by Laufer & Kalovski (2010) and SPSS for calculating self-regulation. Meanwhile, for analyzing data correlation, the Pearson Correlation test was compared with the r-table to determine the accepted hypotheses. The result found that 70% of vocational school students achieve 4.000 to 5.000-word knowledge, and in terms of self-regulation, environmental control became essential for enhancing their learning. Regarding relationship, the significance reached 0.000, with a value of about 0.980 and straightforward. In other words, self-regulation in vocabulary learning has a significant relationship with word knowledge Level about 2.9%, and other variables outside the model explain the other 97.1 %. At the same time, the significance decreased by 0.080. Thus, the higher word knowledge level students get, the lower their self-regulation learning conversely.