Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: Type 2 diabetes is a chronic disease with significant medical burden. eHealth care integrates medicine and technology to enhance such patient outcomes; however, adequate eHealth literacy (eHL) is necessary for that to happen. Fostering eHL is crucial for diabetes patients to engage with eHealth care and receive quality care and timely support. Experiential learning theory can enhance patients’ eHL and skills to use eHealth care technology in their daily care. Objective: This study explored the effectiveness of an eHealth care experiential learning program in improving eHL, patient health engagement, and eHealth usage status among patients with type 2 diabetes. Methods: In this randomized controlled trial, patients under case management services from various clinics were randomly assigned to either the intervention group receiving the six-section eHealth care experiential learning program or the control group receiving usual care. Data were collected using structured questionnaires at three-time points: pre-test, post-intervention, and three months after the intervention. Descriptive data were presented using frequency distribution, percentage, average, and standard deviation. The outcomes were analyzed using a generalized estimating equation by intention to treat analysis. Results: 92 participants (46 in each group) were recruited in this study. Of these, 86 completed the course and follow-up evaluations, with an average age of 62.38 years (standard deviation [SD] = 12.91). After completing the intervention, the intervention group had significantly higher post-test scores in eHL (β = 19.94, standard error [SE] = 3.52, P < .001), patient health engagement (β = 0.28, SE = 0.13, P = .037), and eHealth usage status (β = 3.96, SE = 0.42, P < .001) than that in the control group. Furthermore, the intervention group maintained these significant improvements in eHL (β = 18.19, SE = 3.82, P < .001) and eHealth usage status (β = 3.87, SE = 0.49, P < .001) after three months. Conclusions: Receiving the eHealth care experiential learning program resulted in significant improvements in eHL, patient health engagement, and eHealth usage among patients with type 2 diabetes. Our interventional program can inform future clinical practice and policies to strengthen self-management skills and facilitate the use of health technology in caring for patients with chronic diseases in future clinical practice and procedures. Clinical Trial: ClinicalTrials.gov NCT05180604 (https://clinicaltrials.gov/ct2/show/NCT05180604)