Currently, blended learning (BL) is trending among higher education institutions (HEIs) around the globe. Despite its popularity, no model exists that describes the motivation that affects instructors' opinions and beliefs regarding online learning. Therefore, the purpose of this study is to identify the factors responsible for motivating instructors at HEIs to integrate the BL approach into their courses. Two categories of motivational factors, namely, extrinsic and intrinsic, have been identified in the BL literature. These factors have been used to design a motivation model based on the cause-effect relationship between them. Survey data were collected from 362 HEI instructors in Turkey and North Cyprus for analysis using a structural equation modelling method. The results indicated that both extrinsic and intrinsic motivational factors have a significant impact on the instructors' motivation to apply the BL approach. However, the extrinsic factor, i.e., "academic workload", did not influence the instructors' motivation. In general, the findings confirmed that, the consideration of both extrinsic and intrinsic factors for motivating the application of blended learning has a 79% impact on the adoption of BL. The findings of this study provide practical solutions for educational managers, curriculum designers and faculty members towards creating a cohesive BL environment in HEIs.