This study examine teaching staff supervision and capacity building for quality secondary education delivery in Rivers State of Nigeria. Two (2) research questions and 2 hypotheses were answered and tested in the study, respectively. The design for the study was the descriptive survey, while the population was all the 512 public junior and senior secondary schools in Rivers state, with a corresponding principal population of 512, from where 205 were selected as sample, using the stratified random sampling technique. The participants of the study responded to a validated 19- item instrument titled ‘Teaching Staff Supervision and Capacity Building for Quality Secondary Education Delivery Scale (TSSCBQSEDS), designed by the researchers, in the modified 4-point Likert scale model, with a reliability index of 0.95, obtained using the Cronbach alpha statistics. Mean scores and weighted mean scores were used in answering the research questions, while z.test statistics was used in testing the hypotheses, at 0.05 level of significance. The findings of the study show that teacher’s supervision and capacity building activities enhance quality secondary education delivery and that there is a significant difference between the mean ratings of junior and senior secondary school principals on how the supervision of teachers enhances quality education delivery and no significant difference between the respondents on how teacher capacity building enhances quality education delivery: It was therefore recommended that school administrators should maintain the current tempo in educational supervision apart from continuously building the general capacities of the teachers to bring them in tune with current professional requirements.