The effective application of spherical video-based virtual reality (SVVR) in writing education depends on teachers' lesson design, which is deeply influenced by their technological pedagogical and content knowledge (TPACK). However, how teaching conceptions, as the fundamental viewpoint that influences teachers' teaching focuses, shape their TPACK remains uncertain. This study aimed to explore how teachers' conceptions shape their TPACK regarding SVVR-supported writing instruction. Twenty-one secondary school teachers participated in this study and conducted one semester of SVVR-supported writing lessons. Data were collected through semi-structured interviews, and the interview transcriptions were analyzed using content analysis to explore the association between the teaching conceptions and TPACK. Teaching conceptions were classified into three orientations, namely skill, community, and identity, to reflect the teachers' teaching focuses. TPACK was classified into three categories, namely Replacement, Amplification, and Transformation, to indicate the levels of integrating SVVR into the writing lessons. The results showed that teachers with students' identity-focused conceptions shaped their TPACK at the Transformation level of SVVR integration. Teachers with community-focused conceptions developed students' emotional connections with people and places through their TPACK for deeper writing. Teachers with skill-focused conceptions, on the other hand, shaped their TPACK at the Replacement level that replaced the existing teaching activities and resources with SVVR to teach students writing skills. The findings suggest that teachers may need to shift the conceptions of writing instruction toward identity orientation to develop transformative TPACK.