The internationalization of knowledge-based firms has become increasingly important for economic growth and development, particularly given the limitations of domestic markets and the growing role of knowledge, technology, and innovation in creating competitive advantage. This study aims to identify and explain the key motivations and barriers associated with the entry of knowledge-based firms into international markets. A qualitative research approach was employed, and data were collected through interviews with seven senior executives and marketing managers of knowledge-based firms located in Tehran Province, Iran. Participants were selected using non-probability snowball sampling, and the collected data were analyzed using thematic analysis. The findings revealed that the major motivations for entering international markets include favorable political relations with other countries, geographical proximity, firm survival and growth, access to new technologies, and technological advancement. In contrast, international sanctions, weaknesses in image building and branding, the presence of foreign competitors with well-established brands, political instability, and a shortage of skilled human resources were identified as the main barriers to internationalization. The findings highlight the importance of strengthening research and development activities, expanding industry–university collaboration, participating in international trade exhibitions, developing distribution channels, and improving firms’ understanding of the laws and regulations governing foreign markets. These findings provide practical insights for managers and policymakers seeking to facilitate the international expansion of knowledge-based firms.