Background: eHealth interventions have the potential to enhance health outcomes for people with a low socioeconomic position (SEP), but lack of knowledge on how to effectively meet the specific needs of this population can limit their effectiveness and widen the digital divide. Our study aimed to address this issue by developing an online guide for professionals (e.g., researchers and health professionals) to support the development and adaptation of eHealth interventions for people with low SEP. Methods: During the initial phase, we conducted two studies: (1) a Delphi study with professionals, identifying barriers to developing, evaluating, and implementing eHealth interventions (top-down), and (2) a communitybased study with people from low SEP, exploring their perspectives on health, healthcare, and eHealth (bottom-up). In the second phase, an iterative participatory process was used to develop the online guide, involving 11 professionals in think-aloud sessions and interviews to assess content and design acceptance. The presentation focuses on outcomes of this second phase. Findings: Professionals found the online guide to be user-friendly and helpful, particularly the recommendations on barriers, facilitators, and user scenarios. However, they requested more practical examples and engaging content. Discussion: This guide is an important contribution to addressing the knowledge gap in eHealth interventions for people with a low SEP and provides valuable information for professionals, whether they are new to the field or have experience. Future research should focus on enhancing the guide's usability and flexibility for its diverse audience, including healthcare practitioners, and other eHealth professionals working with this population.