The aim of the study was to explore trajectories of breathlessness intensity by function and life-limiting illness diagnosis in the last 3 weeks of life in palliative care patients. A prospective, consecutive cohort study obtained point-of-care data of patients of Silver Chain Hospice Care Service (Perth, Australia) over the period 2011–2014 (n=6801; 51494 data-points). Breathlessness intensity (0–10 numerical rating scale) and physical function (Australia-modified Karnofsky Performance Status (AKPS)) were measured at each visit. Time was anchored at death. Breathlessness trajectory was analysed by physical function and diagnosis using mixed effects regression. Mean±SD age was 71.5±15.1 years and 55.2% were male, most with cancer. The last recorded AKPS was >40 for 26.8%. Breathlessness was worst in people with cardiorespiratory disease and AKPS >40, and breathlessness in the last week of life increased most in this group (adjusted mean 2.92 versus all others 1.51; p=0.0001). The only significant interaction was with diagnosis and function in the last week of life (p<0.0001). Breathlessness is more intense and increases more in people with better function and cardiorespiratory disease immediately before death. Whether there are reversible causes for these people should be explored prospectively. Omitting function from previous population estimates may have overestimated breathlessness intensity for many patients in the days preceding death.