Background <p>Despite approximately half of the German general population not meeting the physical activity (PA)-guidelines of the World Health Organization with further decreases noted during the pandemic, population-based intervention strategies to tackle this public health problem remain sparse. This study aimed to replicate the successfully delivered “10,000 Steps Ghent” intervention and research trial conducted in Belgium, two research questions were examined: (1) Do individuals located in the city that a complex PA intervention is implemented in (Duesseldorf) engage in more PA compared to individuals located in the control city (Wuppertal) after one year? (2) Is the proportion of those reaching 10,000 steps/day higher in the intervention than in the control city after the intervention?</p> Methods <p>A nonrandomized controlled intervention trial was conducted among residents of two German cities. The 12-month intervention ‘10,000 Steps Duesseldorf’ was designed as a multicomponent intervention targeting different socioecological levels: at the intrapersonal level, a website allowed participants to self-monitor their steps; at the organizational level, workplaces and community groups were engaged through step count competitions; and at the community and policy levels, a city-wide media campaign to increase awareness regarding PA benefits was rolled out and street signage indicating walking routes were posted in different city district of Duesseldorf. To investigate intervention effects, PA was assessed via pedometers in two representative samples of adults aged 25–75&#xa0;years from Duesseldorf (intervention) and Wuppertal (control). Measurements were taken at baseline (April 2021-March 2022) and again one year later (May–November 2023) and the same participants recorded their steps over a 7-day period at both time points. Baseline differences in socio-demographic and health-related variables between intervention and control were adjusted for in a propensity score model with matching weights.</p> Results <p>627 adults completed baseline and 553 the follow-up assessment (60% female, 60% intervention across both timepoints and cities). The results of the propensity score analyses revealed that intervention participants walked an average of 462 steps per day more (95% confidence interval: -146 to 1070) than controls at follow-up. However, the proportion of residents reaching 10,000 steps/day was comparable between intervention and control (Duesseldorf: 26.4%, Wuppertal: 25.6%) after the intervention (odds ratio 1.04, 95% confidence interval: 0.41 to 2.66).</p> Conclusions <p>Although the increase in step count detected in our study was promising, further intervention efforts and accompanying research are needed to meet the&#xa0;minimally relevant intervention effect of 1000 steps that was set in the original Ghent study.</p> Trial registration <p>German Clinical Trials Register DRKS00024873 (Date of registration: April 21st, 2021; URL: <a href="https://drks.de/search/de/trial/DRKS00024873">https://drks.de/search/de/trial/DRKS00024873</a>).</p>