Patients with heart failure experience a high burden of symptoms and physical limitations, and poor quality of life. Dapagliflozin reduces heart failure hospitalization and cardiovascular death in patients with reduced, mildly reduced, and preserved ejection fractions. We examined the effects of dapagliflozin on health status, measured by the Kansas City Cardiomyopathy Questionnaire (KCCQ), across the full spectrum of left ventricular ejection fraction (LVEF). Participant-level data were pooled from the DAPA-HF and DELIVER trials. Both trials were randomized, global, double-blind, placebo-controlled trials of patients with symptomatic heart failure and elevated natriuretic peptides. DAPA-HF and DELIVER included patients with LVEF ≤40% and LVEF >40%, respectively. KCCQ was evaluated at randomization and at 4 and 8 months post-randomization; the effect of dapagliflozin versus placebo on KCCQ total symptom score (TSS) was a pre-specified secondary outcome in both trials. Interaction testing was performed to assess potential heterogeneity in the effects of dapagliflozin versus placebo on KCCQ-TSS, clinical summary score (CSS), overall summary score (OSS), and physical limitation score (PLS), by continuous LVEF using restricted cubic splines. Responder analyses examining the proportion of patients with meaningful deterioration (≥5 point decline) and meaningful improvements (≥5 point increase) in KCCQ-TSS was assessed across LVEF categories. Of 11 007 randomized participants, 10 238 (93%) had full data on KCCQ-TSS at randomization. Benefits of dapagliflozin versus placebo on KCCQ-TSS, -CSS, -OSS, -PLS, at 8 months were consistent across the full range of LVEF (pinteraction = 0.19, 0.10, 0.12, 0.10, respectively). In responder analyses, fewer dapagliflozin- versus placebo-treated patients had clinically meaningful deteriorations in KCCQ-TSS (overall: 21% vs. 23%; LVEF ≤40%: 21% vs. 29%; LVEF 41-60%: 21% vs. 26%; LVEF >60%: 22% vs. 27%). A greater proportion of patients randomized to dapagliflozin experienced at least small improvements in KCCQ-TSS (overall: 50% vs. 45%; LVEF ≤40%: 48% vs. 41%; LVEF 41-60%: 51% vs. 49%; LVEF >60%: 53% vs. 45%). The effects of dapagliflozin versus placebo on clinically meaningful deteriorations and improvements in health status by KCCQ-TSS were consistent across the full spectrum of LVEF assessed continuously (pinteraction = 0.20 and 0.64, respectively). Across the LVEF spectrum, the number needed to treat to affect ≥5 point improvement in health status assessed by KCCQ-TSS was 20. Health status declines preceding a HF hospitalization by ∼10 points were observed in both trials, evident up to 3 months prior to hospitalization. In participant-level pooled analyses of DAPA-HF and DELIVER, dapagliflozin improved all key domains of health status across the full range of LVEF. Clinically meaningful improvements in health status were also observed consistently across LVEF, including in those with LVEF >60%. NCT03036124 and NCT03619213.