Background: In organizational analysis, competence and performance are fundamental issues. To ensure the quality of nursing care, it seems essential to evaluate nurses’ clinical competence (CC) and clinical performance (CP) as the largest group of professionals in the healthcare system. Objectives: This study aimed to examine the CC and CP of nurses and other related factors. Methods: This cross-sectional study involved 220 nurses from various wards of Shahid Beheshti hospital in Kashan, Iran, in 2020. The samples were randomly selected based on the quota assigned to each section (coin toss). Then, 220 selected nurses filled out the CC questionnaire by self-reporting, and among them, the performance of 50 nurses was observed randomly (tossing a coin) in an entire work shift. The data collection tools included a personal information questionnaire and a checklist for evaluating CC and CP. The data were analyzed using SPSS software (version 16; SPSS Inc., Chicago, IL, USA). Data analysis was carried out using descriptive statistical methods, t-tests, analysis of variance, and Spearman and Pearson correlation coefficients. A P-value < 0.05 was considered statistically significant in all tests. Results: The mean age of the participants was 31.15 ± 6.26 years. Moreover, the participants’ mean scores of work experience and work experience in the current ward were 7.57 ± 5.73 and 4.02 ± 3.88 years, respectively. The nurses’ mean scores of CC and CP were 80.79 ± 12.09 (out of 100) and 70.30 ± 11.94 (out of 100), respectively. Female subjects had a significantly higher mean score in terms of CC than male subjects. Additionally, married nurses had a higher mean score than single nurses (P < 0.05). Nurses in the critical care wards and emergency wards scored the highest (89.09 ± 12.09) and lowest (76.39 ± 12.65) regarding CC, respectively, which was statistically significant (P < 0.05). Furthermore, nurses with official employment had the highest mean CC score; nevertheless, nurses with designated employment had the lowest mean CC score, which was statistically significant (P < 0.05). According to the correlation test, nurses’ CC and CP were also associated with age, marital status, work experience in the current ward, and type of employment (P < 0.05). Conclusions: The CP and CC of the nurses participating in this study were satisfactory. Regarding the relationship between the CP score with marital status, workplace sector, employment status, age, general work experience, and current work experience, it is suggested to consider the aforementioned variables in programs for the improvement of nurses’ CP.