Cognitive impairment (CI) is one of symptoms that adults with cancer frequently report. Although there are known factors that contribute to a patient's CI, these factors did not sufficiently explain its variability. Several studies conducted in patients with neurocognitive disorders have reported relationships between patients' cognitive function and caregiver characteristics, which are poorly understood in the context of cancer. This scoping review aims to map the literature on caregiver characteristics associated with CI in adults with cancer. We used the framework proposed by Arksey and O'Malley and PRISMA-Sc. Studies published in English by 2019 were searched through seven electronic databases. All retrieved citations were independently screened and eligibility for inclusion was determined by two independent authors. Ten studies met inclusion for this review with all of them showing significant associations between a patient's cognitive function and caregiver characteristics. Caregiver's mental health was the most commonly associated with a patient's cognitive function followed by family functioning, adaptation to illness, attitude toward disclosure of the illness, burden, coping and resilience, and demographic characteristics. These review findings suggest that enhanced information about CI in relation to caregiver characteristics will eventually provide the foundation for multifocal interventions for patients with impaired cognitive function. This scoping review identified caregiver characteristics that are associated with patients CI. These characteristics should be also assessed when health providers assess and treat CI of adults with cancer.