Soft skills complement hard skills and enable individuals to effectively and efficiently apply their technical knowledge and expertise to achieve organizational goals. This study is applied in its aim and follows a descriptive-exploratory approach. Data were collected using a combination of library studies and fieldwork, including semi-structured interviews and structured questionnaires. The research was cross-sectional and utilized a mixed-methods approach (qualitative-quantitative).In the qualitative phase, soft skills were identified through a review of scientific literature and interviews with start-up founders. These individuals were selected based on criteria such as at least three years of activity, having a marketable product, and compliance with tax regulations. In the quantitative phase, the identified soft skill dimensions were analyzed using the Stepwise Weight Assessment Ratio Analysis (SWARA) technique. This research identified 37 key soft skills through a review of scientific sources and interviews with managers and founders of start-ups based in Mazandaran Science and Technology Park. These skills included communication, negotiation, trust-building, managerial skills, risk management, self-management, teamwork, social skills, and problem-solving. The normalized weights of these skills ranged from 0.0172 to 0.0177, indicating their high importance and ineffective performance. The findings demonstrate that a combination of personal skills, such as analytical thinking, critical thinking, self-management, problem-solving, creativity, and innovation, along with organizational skills, including decision-making and uncertainty management, are considered highly important by the start-up founders studied.