Contribution: While design project courses offer first-year students a practical introduction to engineering, a portion of class time is usually spent on lecturing foundational knowledge instead of practicing engineering design. This article presents a blended design-based learning (bDBL) approach that makes class time more efficient and explores the changes in students' design competencies and intrinsic motivations. Background: Current approaches to cornerstone courses face challenges, such as heavy faculty involvement and heterogeneity of design projects. bDBL draws on the self-directedness of blended learning and the open-ended nature of design-based learning which may be a worthwhile instructional approach for cornerstone courses. Intended Outcomes: bDBL was applied in a cornerstone course that intended to let students understand what engineers do and motivate them in the field. Students' design competencies and intrinsic motivations were examined through pre- and post-self-reported surveys. Focus group interviews were conducted to elicit students' views on bDBL. Application Design: Online self-paced learning modules were created to deliver knowledge-based content. Students transfer what they learned from the online modules through launch-level demos. Then, students spend most of the class time working on team design projects to learn through mistakes and receive first-hand feedback from peers and instructors. Findings: From Fall 2018 to Spring 2020, 201 first-year students experienced bDBL. Quantitative results demonstrated increases in students' design competencies and intrinsic motivations. Four themes representing both positive and negative views of bDBL were elicited. A conceptual framework that connects the theoretical foundation, design elements, examined effects, and students' perceptions, is proposed.