The teaching and learning process is rapidly becoming technology driven with the integration of digital learning using of online learning platforms to facilitate instructional delivery. Google classroom learning platform is one of the effective ways of enhancing student active engagement in an online learning environment. The purpose of this study is to examine the impacts of Google classroom as an online learning delivery platform in secondary school during the COVID-19 pandemic in Nigeria. A mixed method approach was used in the study. Online questionnaire on Google Classroom Attitude Scale (GCAS) was used and online Semi-Structure Interview Guide (SSIG) developed by the researcher for data collection on the students’ perceptions on Google classroom. The researcher used Statistical Package of Social Science programme to calculate and analyse arithmetic mean, standard deviation and t-test. Content analysis was used for analysis of qualitative data. The participants were 140. The results showed that Google classroom platform as an online learning delivery positively affected students' academic achievement, attitudes and their perception during the pandemic in Nigeria’s secondary school. Based on the findings of the study, it was recommended that education stakeholders should effectively prepare students for the use of this platform for their learning activities during the pandemic. The platform is capable of assisting both students and teachers to connect, work together, create assignments, grade students and post learning materials. Likewise, students can also ask questions about the areas they do not understand. Hence, the advantages of the platform can be brought into usage for achieving quality in the teaching and learning process at all levels of education during the pandemic.