Background <p>Emerging evidence suggests that digital therapies are effective for treating obesity; however, an evidence gap exists regarding the potency of stand-alone digital therapeutics with limited additional support from a health care professional. This randomized controlled trial examined the efficacy of a digital health application for weight management in people with obesity.</p> Methods <p>The decentralized digital randomized controlled trial included 164 adults with obesity (BMI 30–45 kg/m²) from Germany who were randomly assigned to either an intervention group (receiving a digital health application for weight management for 6 months) or a control group (receiving care as usual for 6 months). Data on weight (primary endpoint at 6 months), quality of life (WHOQOL-BREF), and food literacy (SFLQ) were collected at baseline, 3, and 6 months.</p> Results <p>Participants (<i>n</i> = 164; 42% female, 58% male) had a mean BMI of 37.82 ± 4.25 kg/m² and a mean age of 45.92 ± 10.66 years. At 6 months, the intervention group achieved a mean weight loss of 5.29% ([95% CI: −6.73% to −3.86%], <i>p</i> &lt; 0.001) compared to 1.76% ([95% CI: −3.10% to −0.42%], <i>p</i> = 0.010) in the control group (estimated marginal mean difference (EMMD): −3.53% [95% CI: −5.16% to −1.91%]; <i>p</i> &lt; 0.001) with a large effect size (<i>d</i> = 0.80, [95% CI: 0.43–1.19]). Compared to controls at 6 months, food literacy (EMMD: 2.77, <i>d</i> = 0.49, <i>p</i> &lt; 0.001) and perceived overall quality of life (EMMD: 0.33, <i>d</i> = 0.40, <i>p</i> = 0.010) improved in the intervention group, though no differences in the four quality of life domains were found.</p> Conclusions <p>The digital health application for weight management demonstrated efficacy in achieving weight loss (&gt;5%) in people with obesity at 6 months.</p> Trial registration <p>This study was registered in the German Clinical Trials Register (Registration number: DRKS00033045).</p>