Patients with newly diagnosed Multiple Myeloma (NDMM) face increasingly complicated treatment regimens, including many medications. E-health may support patients and health care providers during treatment, enhancing patient centered care delivery. Therefore, we aimed to develop a multi-modality e-health application. Furthermore, we aimed to assess the application for usability and end-user experiences and to formulate additional requirements for improvement. The application was developed following an iterative action-based methodology, the Design Thinking approach. Key end-users, including patients, hematologists, pharmacists and nurse specialists, were actively involved. Additional stakeholders, including information technology specialists, secretaries and managers, were consulted during an iterative development process. Before developing the application, the care pathway was evaluated and the ideal care pathway was defined, including integrating an e-health application. Second, the focus of development was determined and a solution ideated during recurring multidisciplinary meetings. Third, mockup display sketches of the intended application modules were recurrently discussed and optimized. Fourth, prototypes were tested and improved. Finally, a final prototype was tested during a pilot study with 18 patients and 7 healthcare professionals, evaluating usability, usage and qualitative experiences. The application, ‘MM E-coach’, consisted of a newly developed medication module (Figure 1), patient reported outcomes (PROs) and experiences questionnaire assessments, a messaging service, threshold-based alerts, information provision and a personal care plan. Following 8 weeks of use, the median system usability scale score was 60. Patients appreciated the medication overview and the healthcare professionals the outpatient clinic preparation module. Both appreciated the messaging service. Several recommendations for improvement were made, for example adding new or more flexible functionalities and improving the application view at a glance. The MM E-coach has the potential to provide patient-centered care by supporting patients and caregivers during Multiple Myeloma treatment and is a promising application to be implemented in the Multiple Myeloma care pathway. Following the recommended improvements, a randomized clinical trial is being conducted to evaluate the clinical effectiveness in hospital practice.