Operating room (OR) nurses’ perioperative competence is vital in operation and patient care. This cross-sectional descriptive study aimed to identify perioperative competencies and educational needs for improving competencies according to the clinical ladder. A total of 318 OR nurses in Korean tertiary hospitals were recruited. Data from the self-reported questionnaire of perioperative competencies, measured on a five-point Likert scale, were used. The average score of perioperative competence was 3.78 ± 0.54; among the sub-categories of competencies were collaboration (4.08 ± 0.55), foundational knowledge and skills (3.98 ± 0.56), proficiency (3.87 ± 0.64), empathy (3.77 ± 0.77), professional development (3.65 ± 0.64), and leadership (3.34 ± 0.89). There were significant differences in perioperative competencies according to the clinical ladder as follows: foundational knowledge and skills (p < 0.001), leadership (p < 0.001), collaboration (p = 0.017), proficiency (p < 0.001), and professional development (p < 0.001). The educational needs for foundational knowledge and skills (4.43 ± 0.60) were highest, and educational needs for proficiency (4.26 ± 0.70), collaboration (4.21 ± 0.77), leadership (4.08 ± 0.81), empathy (3.99 ± 0.91), and professional development (3.91 ± 0.76) were noted. The educational needs for improving perioperative competencies by clinical ladder showed a significant difference in leadership (p = 0.026), proficiency (p = 0.045), and professional development (p = 0.002). In order to develop an effective education program for OR nurses, differentiated education designs that reflect perioperative competencies and educational needs per clinical ladder are necessary.