Loneliness, a subjective negative emotional state that arises from a discrepancy between desired and actual experiences of social connection, is one of the greatest threats to health and well-being across the globe. The relative risks of loneliness to poor health and premature death are comparable to or exceed other prominent causal factors, including smoking, obesity, and depression. Emerging evidence suggests that loneliness is common and clinically relevant in patients with prevalent cardiovascular disease. Although important evidence and practice gaps remain, we outline the reasonable practical steps that clinicians can take to recognize and respond to loneliness within patient-centred cardiovascular care.