Background <p>Physicians with longer clinical experience may accumulate, or conversely exhibit obsolescence of, clinical knowledge and skills.</p> Objective <p>This systematic review aims to summarize current evidence of the impact of physician experience on quality of care and patient outcomes.</p> Methods <p>We conducted a systematic review by searching EMBASE and MEDLINE databases from 2005 to 2025. Studies were included if they evaluated an association between physician experience—either length of practice or age—and quality of care and patient outcomes (i.e., knowledge, adherence to standard of care, and clinical outcome).</p> Results <p>We included 69 studies. Overall, 32 (46%) of 69 studies showed that physicians’ experience or age has a negative impact on the quality of care and patient outcomes, whereas 16 (23%) studies reported a positive impact of experience or age. The negative impact of physician experience was observed in the knowledge and adherence to the standard of care domains: 12 (52%) of 23 studies in the knowledge domain and 14 (61%) of 23 studies in the adherence domain showed a negative effect of experience or age. We found mixed findings for clinical outcomes; six (26%) of 23 studies reported negative and nine (39%) reported positive associations. These relationships were consistent when we limited the studies with low or moderate risk of bias as well as moderate or low certainty of evidence.</p> Conclusions <p>The older age and increased experience of physicians were associated with inferior knowledge and less adherence but not correlated with clinical outcomes.</p>