Background: The diagnostic accuracy of colposcopy is poor for detecting precancerous cervical lesions. Objectives: We assessed the performance of colposcopy for identifying cervical intraepithelial neoplasia grade 2 or worse (CIN2+), before and after including a dynamic spectral imaging (DSI) map that quantifies and maps acetowhitening to assist subsequent biopsy of suspicious lesions. Methods: Four hundred and twenty-five women were examined at a multi-center setting in Wales, of which 393 women were included in the final analysis. Results: For all referrals, the sensitivity of conventional colposcopy for histologically confirmed CIN2+ was 51.5%, the specificity was 92.0%, the positive predictive value was 56.7%, and the negative predictive value (NPV) was 90.4%. With the incorporation of the DSI map in predicting CIN2+, these became 84.8, 61.5, 30.8, and 95.3% respectively. The increase of sensitivity was statistically significant (p < 0.001). For the 236 women having colposcopy after low-grade (LG) cytology, with the incorporation of DSI, the sensitivity for CIN2+ increased from 27.3 to 86.4% (p < 0.001) and the NPV from 92.6 to 97.8%. Conclusions: Colposcopy with DSI results in improved sensitivity to detect CIN2+ and maintains a high NPV for all referrals and especially for those with LG referral cytology.