Background: Women with pathogenic variants (PV) of the genes BRCA1/2 have a choice of preventive options. To help these women decide for themselves, we developed and implemented a decision coaching (DC) program and evaluated it for congruence between the participants’ desired and actual roles in decision-making. Methods: Healthy BRCA1/2 PV carriers (25–60 years of age) were recruited at six centers in Germany. Those who returned baseline (T1) questionnaires were randomly assigned to the intervention group (IG) or the control group (CG). The IG attended a nurse-led DC program. The primary outcome was congruence between the participants’ preferred and actual roles in decision-making. The secondary outcomes were an active role, satisfaction, decisional conflict, and knowledge. The follow-up questionnaires were administered at 12 weeks (T2) and 6 months (T3). Results: Of the 413 women who were recruited, 389 returned the T1 questionnaires. At T2, the groups did not differ significantly in congruence between their preferred and actual roles in decision-making (0.12, 95% confidence interval [-0.03; 0.28], p = 0.128), with a slightly higher congruence in the CG. Women in both groups played a more active role at T2 than their stated preference at T1, with a notably higher percentage in the IG than the CG (IG: 40%, CG: 24.4% [-25.1; -6.1]). IG participants were more satisfied with their role and had less decisional conflict and greater knowledge. Conclusion: This DC program can help women who are carriers of BRCA1/2 PV participate actively in decision-making with regard to preventive measures.