Abstract Aims Subclinical carotid atherosclerosis adds predictive value to traditional risk factors for cardiovascular diseases (CVDs). Systematic Coronary Risk Assessment 2 (SCORE2), an algorithm composed of traditional risk factors, is a state-of-the-art to estimate the 10-year risk of first-onset CVDs. We aim to investigate whether and how subclinical carotid atherosclerosis affects the performance of SCORE2. Methods and results Carotid plaque presence and intima media thickness (IMT) were measured with ultrasound. The SCORE2 was calculated in 4588 non-diabetic participants aged 46–68 years. The incremental value for predicting CVD events of adding carotid plaque or IMT to SCORE2 was evaluated using C-statistics, continuous net reclassification improvement (NRI), and integrated discrimination improvement (IDI). The predicted 10-year CVD risk by SCORE2 and the observed event rate were compared between participants with and without carotid plaque. Adding plaque or IMT to SCORE2 significantly improved performance for predicting CVDs. The improvements in C-statistics, IDI, and NRI of adding plaque to SCORE2 for events occurring during the first 10 years were 2.20%, 0.70%, and 46.1%, respectively (all P < 0.0001). The SCORE2 over-predicted the 10-year CVD risk in those without carotid plaque (3.93% observed vs. 5.89% predicted, P < 0.0001) while under-predicted the risk in those with carotid plaque (9.69% observed vs. 8.12% predicted, P = 0.043). Conclusion Carotid ultrasound adds predictive performance to SCORE2 for assessment of CVD risk. Using SCORE2 without considering carotid atherosclerosis could under- or over-estimate the risk.