There is limited knowledge on the relationship between the living conditions of community-dwelling older people and their quality of life (QOL) considered in all its specific domains. The purpose of this study was to determine (1) which dimensions of QOL were independently associated with living alone and (2) the independent correlates of these dimensions of QOL amongst older outpatients. We conducted a cross-sectional survey of 239 community-dwelling outpatients aged 65+ (mean age 81.5 years) consecutively referred to a geriatric medicine clinic in Italy between June and November 2009 (response rate 93%). Subjects underwent a comprehensive geriatric assessment including QOL, which was evaluated by using the Older People’s QOL questionnaire. In multivariate logistic regression analyses, living alone was associated with the lowest score-based tertile of two specific dimensions of QOL out of seven, namely ‘social relationships and participation’ [odds ratio (OR) 2.73, 95% confidence interval (CI) 1.08–6.91] and ‘home and neighbourhood’ (OR 4.96, 95% CI 1.75–14.07), independently of the main demographic, social, functional and clinical characteristics of the subjects. Amongst the 107 subjects living alone, independent correlates of these dimensions of QOL were depression, having no caregiver and having never been married. Depression, having no caregiver and having never been married could provide a valuable means of identifying older people living alone who are at greater risk of a poor QOL and who would most benefit from effective social and medical interventions.