In order to encourage a shift from the car to the more sustainable transport mode of cycling, cycle streets have been implemented in cities all over the world in the last few years. In these shared streets, the entire carriageway is designated for cyclists, while motorized traffic is subordinated. However, evidence on the impact of cycle street interventions related to travel behavior change has been limited until now. Therefore, the objective of this study was to evaluate whether cycle streets are an effective measure to facilitate bicycle use and discourage car use, thus contributing to the aim of promoting sustainable travel. For this purpose, we conducted a written household survey in the German city of Offenbach am Main involving participants affected by a cycle street intervention (n = 701). Based on two stage models of self-regulated behavioral change (SSBC), we identified the participants’ level of willingness to use a bicycle frequently and to reduce car use. By means of bivariate and multivariate statistical methods, we analyzed the influence of awareness, use, and perceptions of the cycle street on the willingness to change behavior towards more sustainable travel. The results show that the intervention has a positive impact on frequent bicycle use, while we observed only a limited effect on car use reduction. Traffic conflicts and car speeding within the cycle street adversely affect the acceptance of the intervention. The study’s findings provide new insights into the actual effects of a cycle street and its potential to encourage sustainable travel behavior.