The COVID-19 pandemic drastically transformed the global education system forever. To sustain the education system, e-learning has been adopted as an alternative teaching-learning strategy in most countries. Due to this sudden transition, teachers had practically no time to prepare themselves for distance learning, especially in developing countries. Consequently, teachers faced numerous challenges while teaching online. The present study aimed to explore the effectiveness of need-based teachers’ training programs to address online teaching challenges faced by primary and secondary level teachers. Adopting a mixed-method research approach, this study was conducted between January and July 2021 at 6 primary and secondary level institutions in 4 different districts of Bangladesh. Primary data were collected through face-to-face surveys, electronic surveys, and one-to-one semi-structured interviews. Descriptive analysis and bivariate correlational analysis were carried out for quantitative data exploration. On the other hand, qualitative data were coded and analyzed thematically. Findings highlight that less familiarity with online teaching tools, lack of digital skills, unstable Internet connectivity, difficulties with time management, insufficient teaching materials, lack of satisfaction, heavy workload, and poor self-confidence were the key barriers to online teaching. However, in this study, a proper need-based teacher training program is found to be considerably effective in improving online teaching quality by increasing teachers’ technological skills, confidence, satisfaction, motivation, time management skill, and behavioral changes. The overall findings of this study are expected to assist the devolved authorities in implementing synchronized policies to improve online teaching quality.