Science advocacy is a vital tool for ensuring improved and more beneficial science education, especially in resource-poor countries. This study assessed the impact of a train-the-trainer biology workshop (TTTBW) as a useful instrument for science advocacy and maximizing biology teacher training. Thirty-one biology teachers (30% male and 70% female) competitively selected from 25 secondary schools in urban areas of Anambra State Nigeria participated in the two-day TTTBW. They were taught several pre-identified and need-based topics as part of professional development. Some of the topics taught include A) Effective communication skills for biology teaching; B) Teaching management skills; C) Dynamics of child education; D) New pedagogical skills in teaching Biology; E) Strategies for targeted Assessment in Biology; and F) Adaptation of Biology teaching for resource-poor countries. Each topic lasted for at least an hour, and a pre and post-test was done for topics A-C and analyzed. Pre-workshop assessment and post-workshop impact assessment interviews were also carried out through an online form and self-administered questionnaire, respectively. There was a significant increase in the teachers' post-test scores in topics examined (A-C) compared to the pre-test scores (p= 0.00, 0.00, and 0.004 respectively). After the workshop, the interest in teaching biology increased in most of the participants (91%) compared to 23% before the workshop. TTTBW is a potent tool for science advocacy and professional development for teachers and exhibits scale-up potentials for maximal impact.