Banks are more likely to fail from operational risk than from credit risk, and internal control at banks create operational risk losses. This study investigated internal control activities and risk assessment on operational risk of quoted banks in Nigeria. 16 quoted banks from 2013- 2020 were studied based on the 2012 banking reform on corporate governance by the then CBN governor Sanusi Lamido Sanusi’s “Project Alpha Initiative” (PAI).The analysis carried out included pooled OLS regression, fixed and random effect and Hausman tests utilizing E-View 9 software. The findings showed that internal control activities has a negative correlation and internal control risk assessment has positive significant effect on operational risk. The researchers therefore recommend that internal check of staff at banks should be sustained as there was an inverse relationship between internal check and operational risk at banks. Penalties should be spelt out for banking staff who are non-compliant with bank policies and guidelines especially in the area of breech in software codes. Banks should ensure that internal control unit personnel are qualified and adequately trained especially IT staff. Keywords: Internal Control, Control Activities, Risk Assessment and Operational Risk