This study aims to examine the effectiveness of counseling interventions using self-information to increase student career certainty. This study was conducted with a quasi-experimental pre-test--post-test non-equivalent group design. The number of subjects was 94 high school students, out of which 44 were male and 50 were female; the experimental group consisted of 39 people and the control group consisted of 55 people. The Self-information used in this study was provided through the Self-Directed Career Exploration Inventory, while research data was obtained through the Career Plan Certainty Scale. The results showed that career counseling services using self-information were effective in helping high school students to increase their career choice certainty. The mean score of the students of the specialization group in the experimental group increased and was significantly different from the mean score of the students in the control group. In addition, the mean score for the study plans of male and female students was not significantly different.