Objective Because partners are an important and unpaid resource in cancer care, understanding how destructive, controlling or interfering partner behaviors influence women's cancer care may be particularly relevant for health care providers seeking to provide cancer care and enhance recovery. Using a new measure of partner interfering behaviors in cancer care (PIB‐C), we investigated whether women with a recent cancer diagnosis who additionally endorsed any PIB‐C would report (a) more symptoms of depression and stress, and (b) lower Functional Assessment of Cancer Therapy (FACT‐G) and lower Functional Assessment of Chronic Illness Therapy‐Spiritual Well‐being (FACIT‐SP) scale scores indicating poorer quality of life (QOL). Methods Women aged 18–79 included in cancer registries as having an incident, primary, biopsy‐confirmed cancer in the past 12 months were eligible for this study. Consenting women completed a phone interview 9–12 months following cancer diagnosis between 2009 and 2015. Interviews provided data to measure outcomes (perceived stress and depressive symptoms, FACIT‐SP and FACT‐G scores), partner supportive and interfering behaviors, and other potentially confounding factors. Results Of the 2376 women in a relationship at cancer diagnosis, 14.7% endorsed one or more of 14 PIB‐C items. Women endorsing any PIB‐C item reported more symptoms of depression and stress and lower FACT‐G and FACIT‐SP scores than partnered women reporting no PIB‐C even when controlling for partner supportive behaviors and lifetime intimate partner violence. Increasing PIB‐C scores were also correlated, in a dose–response pattern, with these same outcomes. Conclusions Partner interfering behaviors during cancer care impact patients' QOL across multiple domains. © 2016 The Authors. Psycho‐Oncology Published by John Wiley & Sons Ltd.