Introduction and Aims: In July 2016, the Queensland government introduced the Tackling Alcohol-Fuelled Violence policy, with some amendments over the subsequent 12 months. Key measures included restricting alcohol sales to 3 am in safe night precincts (SNPs), limiting the annual number of extended trading permits (i.e. trading until 5 am) and introducing mandatory networked identification scanners. We examined the policy impact on the number of serious assaults across all combined SNPs and in five major SNPs: Fortitude Valley, Cairns, Surfers Paradise, Toowoomba and Townsville. Design and Methods: Using police data (July 2009–June 2019), we examined the impact of the policy on serious assaults during high-alcohol hours (high-alcohol hours; 8 pm–6 am, Friday and Saturday), employing time series methods. Results: Across all SNPs there was no significant change in the number of serious assaults during overall high-alcohol hours, but a significant 49% decrease in the monthly number of serious assaults between 3 am and 6 am on Friday/Saturday. A significant decrease in the monthly count of serious assaults during high-alcohol hours and specifically 3 am–6 am on Friday/Saturday was evident in Fortitude Valley SNP (52%), and during high-alcohol hours in Toowoomba SNP (43%). Discussion and Conclusions: Although results were mixed, there was evidence of some promising reductions in alcohol-related violence in SNPs. It is likely that factors such as extended trading permits (venues not closing at 3 am), continued drinking in some venues and 24-h trading in casinos have reduced the potential impacts seen elsewhere.