Background Antiretroviral therapy (ART) initiation on the day of an HIV diagnosis or as soon as possible after diagnosis, known as rapid ART (henceforth “RAPID”), is considered to be a safe and effective intervention to quickly reduce viral load and potentially improve engagement in care over time. However, implementation of RAPID programming is not yet widespread. To facilitate broader dissemination of RAPID, we sought to understand health care worker experiences with RAPID implementation and to identify essential programmatic elements. Methods We conducted 27 key informant interviews with medical providers and staff involved in RAPID service delivery in three distinct clinical settings: an HIV clinic, a Federally Qualified Health Center and a sexual health and wellness clinic. Interviews were structured around domains associated with the Consolidated Framework for Implementation Research and were audio-recorded, transcribed, and thematically analyzed. Findings We identified seven (7) essential elements across settings associated with successful RAPID program implementation. These high-impact elements represent essential components without which a RAPID program could not function. There was no one requisite formation. Instead, we observed a constellation of essential elements that could be operationalized in various formations and by various people in various roles. The essential elements included: (1) presence of an implementation champion; (2) comfort and competence prescribing RAPID ART; (3) expedited access to ART medications; (4) expertise in benefits, linkage, and care navigation; (5) RAPID team member flexibility and organizations’ adaptive capacity; (6) patient-centered approach; and (7) strong communication methods and culture. Conclusions The RAPID model can be applied to a diverse range of clinical contexts. The operational structure of RAPID programs is shaped by the clinical setting in which they function, and therefore the essential elements identified may not apply equally to all programs. Based on the seven essential elements described above we recommend future implementers identify where these elements currently exist within a practice; leverage them when possible; strengthen them when necessary or develop them if they do not yet exist; and look to these elements when challenges arise for potential solutions.