Objective We evaluated the effect of a digitally supported systems intervention for suicide prevention (SUPREMOCOL) in Noord-Brabant, the Netherlands. Method Non-randomized stepped wedge trial design (SWTD). Stepwise implementation in the five subregions of the systems intervention. Pre-post analysis for the whole province (Exact Rate Ratio Test, Poisson count). SWTD Hazard Ratios of suicides per person-years for subregional analysis of control versus intervention conditions over five times three months. Sensitivity analysis. Results Suicide rates dropped 17.8% (p = .013) from 14.4 suicides per 100,000 before the start of implementation of the systems intervention (2017), to 11.9 (2018) and 11.8 (2019) per 100, during implementation; a significant reduction (p = .043) compared to no changes in the rest of the Netherlands. Suicide rates dropped further by 21.5% (p = .002) to 11.3 suicides per 100,000 during sustained implementation in 2021. Sensitivity analysis confirmed the reduction (p = .02). The SWTD analysis over 15 months in 2018–2019 did not show a significant association of this reduction with implementation per subregional level, probably due to insufficient power given the short SWTD timeframe for implementation and low suicide rates per subregion. Conclusions During the SUPREMOCOL systems intervention, over four years, there was a sustained and significant reduction of suicides in Noord-Brabant.