In patients with early breast cancer, personal and tumour characteristics other than family history are increasingly used to prompt genetic testing to guide women’s cancer management (treatment-focused genetic testing, ‘TFGT’). Women without a known strong family history of breast and/or ovarian may be more vulnerable to psychological sequelae arising from TFGT. We compared the impact of TFGT in women with (FH+) and without (FH−) a strong family history on psychological adjustment and surgical decisions. Women aged <50 years with high-risk features were offered TFGT before definitive breast cancer surgery and completed self-report questionnaires at four time points over 12 months. All 128 women opted for TFGT. TFGT identified 18 carriers of a disease-causing variant (50.0% FH+) and 110 non-carriers (59.1% FH+). There were no differences based on family history in bilateral mastectomy (BM) uptake, p = .190, or uptake of risk-reducing bilateral salpingo-oophorectomy (RRBSO), p = .093. FH− women had lower decreases in anxiety a year after diagnosis, p = .011, and regret regarding their decision whether to undergo BM, p = .022, or RRBSO, p = .016 than FH + women. FH− carriers reported significantly higher regret regarding their TFGT choice (p = .024) and test-related distress (p = .012) than FH + carriers, but this regret/distress could not be attributed to a concern regarding a possible worse prognosis. These findings indicate that FH− women may require additional counselling to facilitate informed decisions. Carriers without a family history may require additional follow-up counselling to facilitate psychological adjustment to their positive variant results, extra support in making surgical decisions, and counselling about how best to communicate results to family members.