Project Safe Neighborhoods (PSN) is an increasingly popular violence and gun crime prevention program which aims to identify prolific violent offenders, and deter or incapacitate them from offending. While PSN programs generally show moderate effects on violence and gun crime reduction, questions remain about the magnitude and duration of effects given the heterogeneity in treatment applications across PSN programs. This study presents a quasi-experimental evaluation of a cutting-edge PSN initiative on violence and gun crime in Tampa, Florida over a 6-year period. Results indicate that PSN was associated with a 24.4% raw reduction in violence (d = −0.16) and a 24.0% reduction in gun crime rates (d = −0.22) for the treatment agency, while the control groups saw much smaller decreases in violence and gun crime over the same time period. There are several policy implications, as PSN is currently endorsed by the U.S. Department of Justice to combat violence and gun crime, with billions spent to support these programs across the nation. First, this study suggests that the use of an objective scoring criteria comprised a multi-faceted array of evidence-based risk factors to identify the prolific offenders subject to the PSN intervention yields a notable effect on violence and gun crime reduction and unlike other PSN initiatives, this program benefits from not being reliant on more subjective or sweeping approaches to identify potential prolific offenders. Second, this approach was associated with substantial decreases in violence and gun crime over the 3-year follow-up period, but importantly, total arrests in the treatment jurisdiction also decreased. This has potential positive effects for police-community relations, and perceptions of police legitimacy and effectiveness. Finally, the crime reductions in this evaluation were estimated to prevent more than 250 victims of violence and gun crime, and provide support for a new approach for PSN initiatives to replicate in research and practice.