This study determined the relationship between knowledge and anxiety levels of frontline nurses during the Covid-19 pandemic in Prince Sultan Military Medical City, Riyadh with the use of descriptive correlation cross-sectional research design, and the data were collected using a survey questionnaire and adopted the GAD-7 Anxiety tool. Respondents of the study were the 290 employees chosen purposively. The present study reveals that most of the respondents belonged within the age range of 31-36 (52.41%), female (90%) with O+ blood type (41.03%), bachelor's degree in nursing (82.41%), staff nurse 2 (49.31%), had 6 – 10 years work experience (40.69%), classified as a technician (50.69%) and currently working at the emergency unit (22.07%). Similarly, the mean knowledge about Covid-19 was 21.82 verbally described as "very good knowledge." Meanwhile, (59.66%) of the respondents had very good knowledge about Covid-19. The computed mean anxiety level of the respondents was 5.89 verbally described as "moderate anxiety," about (48.97%) had mild anxiety. Furthermore, the socio-demographic profile of the respondents does not significantly correlate to the knowledge about Covid-19 and anxiety level, which leads to the acceptance of the null hypothesis. Finally, there are no significant variations existed in the knowledge about Covid-19 and anxiety level when grouped according to socio-demographic variables which lead to the acceptance of the null hypothesis.