Online tutoring is crucial for pre-university students, as it provides academic support and helps them develop the essential skills needed for a successful transition to higher education. With the widespread shift to remote learning, online tutoring has emerged as both an intervention and an alternative to traditional instruction. Despite its relevance, existing studies have emphasized factors influencing adoption and effectiveness, while paying limited attention to systematically exploring the barriers to its successful implementation. To address this gap, this work aims to identify and analyze the barriers to online tutoring in the context of pre-university education in the Philippines. The study design comprises two sequential components. First, a systematic literature review guided by the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework is conducted to determine a comprehensive initial list of barriers. The initial list was validated by a group of experts tasked with evaluating the relevance of barriers in the pre-university context. Second, to analyze these barriers, the DEMATEL (Decision-Making Trial and Evaluation Laboratory) approach was used to identify critical barriers and map their significant structural interdependencies. The findings of the systematic literature review reveal 13 barriers to online tutoring, including unstable connectivity, inadequate device access, low digital literacy, insufficient pedagogical training, weak content knowledge, poor instructional adaptation, low student engagement, reduced feedback quality, cultural mismatch, poor platform usability, inflexible scheduling, low motivation, and inadequate institutional support. Exploring their interdependencies shows that insufficient pedagogical training and low digital literacy are the key driving barriers that significantly influence online tutoring in pre-university education. When addressed, they contribute to mitigating poor instructional adaptation, low student engagement, reduced feedback quality, and low student motivation to engage in online tutoring. By providing a structured relationship map, this study offers practical insights to guide educators and policymakers in developing targeted interventions and improving implementation.