Background <p>Hypertension, a major concern for older adults, contributes to morbidity and mortality by increasing the risk of cardiovascular disease, stroke, kidney dysfunction, and cognitive decline. A healthy diet plays a vital role in limiting chronic disease progression in aging populations.</p> Aim <p>This study investigated the association between diet quality and healthy aging, focusing on blood pressure measurements (BPMs), using the Canadian Longitudinal Study on Aging (CLSA).</p> Methods <p>Participants aged 45–85 years at baseline were followed for up to nine years. Mediterranean diet score (MDS) was determined based on the validated short diet questionnaire (SDQ). BP and mean arterial pressure (MAP) were measured at baseline (2010), follow-up 1 (2015), and follow-up 2 (2018). Linear regression models (LRMs), linear mixed-effects models (LMMs), and latent change score models (LCSMs) examined the associations and longitudinal effect between MDS and BPMs, adjusted for potential confounders. Individuals who participated in all three waves (<i>n</i> = 25,377) were included.</p> Results <p>Fully adjusted LRMs showed significant (<i>p</i> &lt; 0.001) inverse associations between MDS and all BPMs across all time points, e.g., 1 unit increase in the MDS (min0-max50) was associated with a 0.058 mmHg decrease of diastolic BP (DBP) (β=-0.058), 0.052 mmHg systolic BP (SBP) (β=-0.052), and 0.056 mmHg MAP (β=-0.056). LCSMs indicated that a 1-unit higher baseline MDS was significantly associated with 0.090 mmHg reductions in DBP at follow-up 2 (β=-0.090,<i>p</i> &lt; 0.001), 0.078 mmHg for SBP (β=-0.078,<i>p</i> = 0.002) and 0.076 mmHg for MAP (β=-0.076,<i>p</i> = 0.003). Changes in MDS during follow-ups showed no consistent significant associations with BPMs at follow-up 1 or 2.</p> Discussion and conclusion <p>Higher MDS was associated with lower BPMs over time. This study highlights the role of diet quality in healthy aging and mitigating cardiometabolic risk in older adults.</p>