Heartwheels! STEM Mobile Outreach is a scientist-led collaborative, innovative, and reproducible experiential educational program and mobile lab developed to engage people young and old in the cardiovascular sciences, improve health literacy and awareness of heart-healthy living, and spark curiosity in the science, technology, engineering, and mathematics (STEM) fields. Applied hands-on interactive activities at Heartwheels! events include heart dissection, cardiovascular physiology, and mock flow loops (science); medical devices (technology); instrumentation and sensors (engineering); and calibration and validation methods and models (math). These modules are complementary to school activities and are particularly successful from an educational standpoint because they are fun, interactive, engaging, voluntary, open-ended, and not graded or assessed and can lead participants and their families to develop STEM-positive identities. Primary learning objectives include a broad understanding of cardiovascular anatomy and physiology, advanced technologies and emerging medical devices, and the benefits of a heart-healthy lifestyle and stimulating interest, building self-confidence, and helping participants envision themselves participating in and making potentially significant contributions to STEM fields. To date, 11,229 attendees of all ages and backgrounds have participated in 55 Heartwheels! events. Excellent programmatic ratings (1-5 scale: 1 = poor, 5 = excellent), including 94.5% of participants self-reporting that it was a fun educational experience and 96.6% reporting that they learned new things, with complimentary verbal and open-ended written feedback, demonstrate the significant impact and value that Heartwheels! and hands-on experiential educational events contribute to diverse, resource-limited, and underserved communities.