Introduction: Brief interventions delivered using mobile technologies have become popular to reduce youth alcohol use, however, few have been applied to cannabis use and driving under the influence of cannabis (DUIC). This Delphi study sought to create and compare consensus among a panel of experts (potential intervention developers) and a panel of youth (intervention audience) on the characteristics to prioritize in a youth DUIC mobile-based brief intervention. Methods: A two-round two-panel Delphi study was conducted among 26 professionals with expertise in youth substance use and impaired driving and 20 youth who use cannabis. Participants ranked the importance of 45 evidence-informed intervention characteristics using a 7-point Likert scale. Characteristics that received an interquartile deviation score <= 1 (indicating consensus) and a median score of >= 6 (indicating importance) in both panels were considered shared priorities. Differences in panel rankings were quantified using Mann-Whitney U tests. Results: Consensus was achieved for 41 characteristics in the professional panel and 34 in the youth panel, with ratings generally higher among professionals. Overall, 16 shared priorities emerged. These include critical theoretical characteristics (e.g., self-efficacy, motivation, overcoming barriers), practical characteristics (e.g., mobile availability, estimates of intervention length, ability to input behaviours) and core contents (e.g., real-life stories, education on the risks/dangers, appropriate messaging). Youth's perceptions on the dangers of DUIC received the most support for an intervention outcome. Conclusions: Findings can inform the development of mobile-based brief interventions for youth, an essential step in reducing DUIC among youth and addressing this public health concern.