Objectives <p>This case-series study intensively explored the evolution of craving, perceived control over problematic behavior, and relapse risk in nine individuals undergoing treatment for behavioral addictions (predominantly gambling disorder) during an 8-week mindfulness training program. The study aimed to examine the acute and cumulative changes in these variables and their associations with mindfulness exposure.</p> Method <p>Participants engaged in daily self-assessments via an online diary across five consecutive phases: baseline, 4-week mindfulness training, return to baseline, second 4-week training, and final return to baseline. During return-to-baseline periods, guided sessions were suspended, though trainees could continue meditating independently. A mixed-effects modeling approach, tailored for case-series data, was used to assess associations of the outcome variables with training duration, cumulative meditation practice, and temporal proximity to a mindfulness session, either guided or autonomous.</p> Results <p>Analyses revealed improvements across most trainees and outcome measures, though with notable variability. Sustained improvements in craving, gambling control, and relapse risk were primarily associated with accumulated mindfulness practice, while acute session-related changes were modest and limited to craving.</p> Conclusions <p>Although causal relationships cannot be definitively established due to the case-based design, consistent mindfulness engagement emerged as a key within-individual correlate of symptom reduction. These findings highlight the feasibility of linking symptom dynamics to individual training engagement and underscore the value of fine-grained analyses complementing traditional randomized controlled trials (RCTs).</p> Preregistration <p>This study was not preregistered.</p>