There is limited evidence regarding implementing organisational improvements in the cultural responsiveness of non-Aboriginal services. Using a pragmatic implementation process to promote organisational change around cultural responsiveness, we aimed to (i) identify its impact on the cultural responsiveness of participating services; (ii) identify areas with the most improvement; and (iii) present a program logic to guide cultural responsiveness. A best-evidence guideline for culturally responsive service delivery in non-Aboriginal Alcohol and other Drug (AoD) treatment services was co-designed. Services were grouped geographically and randomised to start dates using a stepped wedge design, then baseline audits were completed (operationalization of the guideline). After receiving feedback, the services attended guideline implementation workshops and selected three key action areas; they then completed follow-up audits. A two-sample Wilcoxon rank-sum (Mann–Whitney) test was used to analyse differences between baseline and follow-up audits on three key action areas and all other action areas. Improvements occurred across guideline themes, with significant increases between median baseline and follow-up audit scores on three key action areas (median increase = 2.0; Interquartile Range (IQR) = 1.0–3.0) and all other action areas (median increase = 7.5; IQR = 5.0–11.0). All services completing the implementation process had increased audit scores, reflecting improved cultural responsiveness. The implementation process appeared to be feasible for improving culturally responsive practice in AoD services and may be applicable elsewhere.