The COVID-19 pandemic has compelled innovations in science teaching and learning, such as blending online sessions with conventional face-to-face classes. We developed and validated the Blended Laboratory and E-learning iNstructional Design (BLEND) model for university-level remote laboratory sessions (RLS) to respond to the fluctuating instructional environment necessitated by the pandemic. We used the design and development research method to construct and apply an ID model in an analytical chemistry experiment (ACE) course for pre-service chemistry teachers, iteratively revising the model with participant feedback. We based the initial BLEND model on a literature review and lessons from our preliminary study in 2020. For internal validation, six stakeholders participated in the usability test, and 10 science subject-matter educators and three educational technology experts provided expert reviews. For external validation, we developed and implemented an ACE-RLS course module, and surveyed and interviewed seven university students who took the course. After two rounds of validation, the BLEND model was confirmed to be internally efficient and externally effective, with interactions between the instructor and students particularly appreciated. The final BLEND model for university-level RLS emphasizes constant formative evaluation, feedback, and structures and visualizes the RLS instructional system at both weekly and overall course levels.