The study examined the influence of classroom observation towards improving the classroom interactive pattern of Secondary School science teachers in Nigeria. It focused on the effect of observation during classroom teaching by the teachers. The targeted classroom interaction patterns for the study are: questioning, students’ involvement, class control, body gesture and students’ motivation. The study adopted the pre-test post-test quasi experimental research design. The population for the study was the secondary school science teachers in Nigeria out of which a sample of 108 were selected through multistage sampling techniques across three geo-political regions of the country. There were two research questions and three null hypotheses tested at 0.05 significant level. The study adopted the Adedayo’s [1] Classroom Behaviour Analysis Chart (CBAC) as the research instrument. The observation of the teachers’ classroom interaction was done by video recording of the teachers’ activities during lessons through Android phones by the research assistants. The data obtained were analysed using descriptive and inferential statistics of mean scores, percentages, correlation and t-test at 0.05 level of significance. The result of findings revealed that classroom observation influences the classroom interaction pattern of secondary school science teachers in Nigeria, irrespective of teacher’s gender. It was recommended that teachers should regularly observe their classroom teachings towards improving their classroom interaction capable of engendering effectiveness.