Purpose This article outlines the rationale and development process for an online intervention based on vestibular rehabilitation therapy (VRT). The intervention aims to assist adults aged 50 years and older to self-manage and reduce dizziness symptoms. Method The intervention was developed according to the person-based approach to digital intervention design focused on accommodating perspectives of target users. A prototype version of the intervention was provided to 18 adults (11 women, 7 men) aged 50 years and older with dizziness. These adults were invited to use the intervention over a 6-week period and, during this time, took part in a think-aloud session. This session sought to understand users' perceptions of how acceptable, engaging, and easy to use they found the online intervention. Results Users were extremely positive regarding how easy to navigate, visually appealing, and informative they found the intervention. Think-aloud sessions provided valuable data for informing small amendments to further enhance acceptability of the intervention for target users. Conclusions Informed by these development-phase data, a finalized version of the intervention is now being investigated in a primary care–based randomized controlled trial. Results should provide an understanding of whether VRT can be effectively—especially, cost-effectively—delivered via an online intervention to adults aged 50 years and older.