Inquiry-based science education (IBSE) is a student learning management strategy focusing not only on the active construction of knowledge in the natural sciences. Through the used educational procedures, it also develops students' soft skills. The impact of IBSE on the development of soft skills was monitored in a group of 14- to 15-year-old students in Czech basic schools. The main aim of the study was to determine whether IBSE contributes to greater development of students' self-assessment of the achievement level of selected soft skills compared to the transmissive model of managing their learning activities. The study employed an educational experiment as its validation method. The experimental group (N = 232) received IBSE teaching over a five-month period, delivered by teachers who had received prior IBSE training and were regularly supervised by the research team. The control group (N = 207) was taught using the transmission model for the same duration. Soft skill self-assessment was conducted using an 80-questions questionnaire based on interval scales. For each skill, the level of self-assessment was calculated as the arithmetic average of respondents’ ratings across 10 items. The collected data were analysed using descriptive and inferential statistical methods. The results show that students taught using IBSE reported significantly higher self-assessed levels in communication, teamwork, problem-solving, creativity, and the ability to learn new things compared to the control group. IBSE appears to be an effective educational model that not only supports science literacy but also fosters the development of key soft skills applicable in real-life and out-of-school contexts.