Background: Suctioning is one of the nursing interventions frequently applied in clinical and intensive care units. In order to perform suctioning correctly and effectively, it is important for nursing students to acquire and develop this skill during their undergraduate theoretical and practical education. Objectives: The study aims to reveal the knowledge levels and evidence-based approaches of nursing students about suctioning practices. Design: The study is a descriptive and cross-sectional study. Settings: It was carried out in the Faculty of Nursing of two state universities in Konya between March and June 2022. Participants: A total of 506 undergraduate students participated in the study. Methods: Data were collected using the Personal Information Form, the Knowledge of Suctioning Questionnaire, and the Attitude towards Evidence-Based Nursing Questionnaire. Data were analyzed by calculating number, percentage, mean, and standard deviation, and using the multiple linear regression analysis. Results: The mean Attitude towards Evidence-Based Nursing Questionnaire score of the students was found to be 63.04 ± 7.91, and their mean Knowledge of Suctioning Questionnaire score was 33.46 ± 14.63. 83.8 % of the students obtained a low score from the questionnaire. Senior students had high scores on the Attitude towards Evidence-Based Nursing Questionnaire, which are significant predictive variables affecting the level of knowledge about suctioning (p < 0.05). Conclusions: It was found that the high scores of the students on the Attitude towards Evidence-Based Nursing Questionnaire had an effect on their level of suctioning knowledge. The study also revealed that being a fourth-year student and receiving training on suctioning affected the level of suctioning knowledge.