This study investigates how cognition influences activities of daily living and health-related quality of life in 85-year-olds in Sweden (n = 373). Data collection included a postal questionnaire comprising demographics and health-related quality of life measured by the EQ-5D. The ability to perform personal activities of daily living (PADL) was assessed during a home visit that included administering the Mini Mental State Examination (MMSE). Cognitive impairment was shown in 108 individuals (29%). The majority were independent with respect to PADL. A larger number of participants with cognitive impairment reported that they needed assistance in instrumental activities of daily living (IADL) compared to the group without cognitive impairment. Impaired cognition was significantly related to problems with IADL. Significant but low correlations were found between cognition and health-related quality of life - higher ratings on perceived quality of life correlated with higher results on the MMSE.