Objective: This article evaluates the treatment effectiveness of an integrated intervention compared with addiction treatment as usual in reducing intimate partner violence perpetration (IPV-P) among patients in a drug addiction intervention program. Method: A parallel, randomized, controlled trial was carried out with repeated measures of assessment (pretreatment, posttreatment, and 6-month follow-up). A sample of 227 consecutive patients was assessed, and 70 patients with IPV-P were selected to participate in the study and then divided into two groups: treatment (n = 34) and control (n = 36). The treatment group participated in an integrated intervention program for addiction and IPV-P, and the control group received the treatment as usual without intervention for IPV-P. Treatment success was defined as the complete absence of IPV-P episodes, both physical and psychological. Results: At the follow-up, the patients in the treatment group showed an IPV-P success rate (60.7%) that was significantly higher (χ2 = 3.85; p < .05) than that of the patients in the control group (31.6%). Moreover, both groups achieved statistically significant improvements in associated variables. Conclusions: The presence of IPV-P should be assessed in drug addiction treatment programs. The combined treatment for addiction and IPV-P seems to be effective.