<p>This study utilizes a mixed-methods approach to investigate the development of technological pedagogical content knowledge (TPACK) and the integration of information and communication technology (ICT) in the collaborative lesson planning (CLP) activities among a group of pre-service teachers. A survey instrument based on the TPACK framework was employed to measure their TPACK levels across the CLP procedure. Additionally, an online collaborative learning tool was used to facilitate lesson planning and simulated teaching practices. Key findings include improvements in the pre-service teachers’ TPACK levels after the CLP, particularly in the technology-related domains. The integration of ICT tools was found to be strategic and context-aware, with pre-service teachers selecting tools that aligned with learning content and pedagogy. This study provides insights into the impact of CLP on TPACK development and ICT integration, offers practical strategies for future teacher education, and highlights the importance of a balanced approach to technology integration in lesson planning and teaching practices.</p>