Background <p>Most individuals self-excluding from gambling have lost control over their gambling behavior. Commercial solicitations are prohibited during the self-exclusion period, but resume immediately afterwards. The self-exclusion system appears insufficient, particularly for short self-exclusions and among the heaviest gamblers. We assessed the impact of extending suspension of commercial solicitations on gambling intensity.</p> Methods <p>In this parallel randomized study, we included 2548 French online gamblers who self-excluded for up to 3&#xa0;months from May–November 2022. They were assigned 1:1 to optimized self-exclusion with extended commercial solicitations ban for 9&#xa0;months or standard procedure. The primary outcome was the change in total loss over the past 4&#xa0;weeks at Month 9. We also assessed total deposit, total stakes, compulsivity, number and duration of gaming sessions and subsequent self-exclusions at 6, 9, 12 and 18&#xa0;months.</p> Results <p>Participants were randomized to the optimized group (n = 1265) or standard group (n = 1283). The results didn’t show a significant difference in the reduction in total losses. The optimized group showed significantly reduced 4-week total deposits versus standard group at 6&#xa0;months (455.68 euros vs. 319.65 euros, <i>p</i> = 0.017), 9&#xa0;months (451.92 euros vs. 343.21 euros, <i>p</i> = 0.040), and 12&#xa0;months (484.27 euros vs. 370.02 euros, <i>p</i> = 0.025). Significance was lost at 18&#xa0;months (492.61 euros vs. 404.73 euros, <i>p</i> = 0.087).</p> Conclusions <p>An extended 9-month ban on direct commercial solicitations after self-exclusion significantly reduces gambling deposits during, and 3&#xa0;months after, the ban. This supports the effectiveness of improving self-exclusion procedure. Future research should explore longer bans and indirect commercial solicitations.</p> <p><i>Trial registration</i>: NCT05413564.</p>