Following the recent developments in information and communication technologies (ICT), educators cannot opt-out using technology in educational settings. Yet, research studies have indicated that teachers' lack of ICT knowledge is considered among the barriers for successful technology integration. Within this framework, this study aimed at documenting the perceptions of in-service teachers about individualized technology-related (ITR) mentoring processes based on the TPACK model. The ITR mentorship provided one-to-one mentoring sessions lasting two semesters at the schools where the teachers worked. The collaboration between the mentor and the mentee (teacher), called ITR mentorship, included not only the support for technological needs of the teachers but also preparing course materials for teaching specific content of the subject. Through mixed methodology, quantitative and qualitative data were collected from participating 31 (17 mathematics and 14 language) teachers. At the end of the study, the change in perceived TPACK levels of teachers was quantitatively examined and qualitatively supported with their views on this process. It was found that technology-related TPACK constructs significantly increased through one-to-one mentoring due to its non-threatening atmosphere, enabling flexible time and content, and addressing the needs of the teachers. In the light of these findings, the ITR mentorship can be suggested for the professional development of teachers and considered for in-service teacher trainings.