There has been a growing number of mobile health (mHealth) smartphone applications (apps) that target smoking cessation. There is concern that many smartphone apps for smoking cessation lack evidence-based practices, which harms the apps’ efficacy and effectiveness. Two evidence-based mHealth apps that target smoking cessation are Acceptance and Commitment Therapy (ACT)-based 2Morrow Quit™ (2Q) and mindfulness-based Craving to Quit® (CTQ). 2Q is based on the ACT framework that teaches strategies to increase acceptance and reduce experiential avoidance, while making values-guided committed behaviour changes. CTQ is based on mindfulness training (MT) that teaches techniques to decouple the link between craving and smoking, established by associative and reinforcing processes. This study’s purpose was to examine the effectiveness of 2Q and CTQ using a single-subject A1-B-A2-A3 design with a broad recruitment strategy that included anyone worldwide. There were two main areas explored: (1) to examine if ACT-based 2Q would reduce cigarette intake and cravings to smoke when compared to CTQ; and (2) to examine if having greater acceptance and commitment during post-intervention would predict better smoking outcomes (i.e., reduced cigarette consumption, reduced cravings, or quit smoking) when compared to CTQ. There was evidence of a small reduction in cigarette consumption for both intervention groups but was not statistically significant. There was limited evidence that both interventions were effective in reducing cravings to smoke because of observed differences, and no statistical significance found. There was limited evidence that higher acceptance and commitment levels predicted better smoking outcomes. It is speculated that 2Q is more engaging than CTQ; however, in terms of effectiveness, it is necessary to replicate this study with a larger sample size to produce adequate statistical power.