Background: Nomophobia, short for no mobile phobia, is the fear of being without a smartphone. Nomophobia is common, especially in the young population, with an increase in the use of technology in society. Objectives: This study aimed to determine the nomophobia levels of nursing students and the relationship between nomophobia and personality traits. Methods: This multicenter, descriptive, and relational study was carried out in three different universities. The students were reached via the Web-Anket application within June to July 2021. The nursing department students in Turkey (n = 818) constituted the research population. No sample selection was performed in the study, and all students who accepted to participate and met the inclusion criteria were included in the study. The study was conducted on 424 nursing students. The data were collected via an online personal information form, Nomophobia Questionnaire, and 10-Item Personality Inventory (TIPI). Percentage, mean ± standard deviation, analysis of variance, and Pearson correlation coefficient tests were used to analyze the data. Results: The mean age of the participants was 20.5 ± 1.8 years. Moreover, 84.7% of the participants were female. Additionally, 93.2% of the subjects lived with their parents, and 63.0% reported that the monthly income of the family was equal to monthly expenditures. It was shown that 31.1% of the students had mild nomophobia; nevertheless, 52.6% and 16.3% of the students had moderate and severe nomophobia, respectively. The total nomophobia score was observed to be 74.17 ± 25.53. The TIPI subdimensions’ mean scores were 9.87 ± 2.29, 8.83 ± 2.33, 8.66 ± 2.82, 10.66 ± 2.65, and 9.34 ± 3.04 for openness to experience, agreeableness, emotional stability, conscientiousness, and extroversion, respectively. This study revealed that students’ smartphone usage purposes and personality traits were related to their nomophobia levels. Conclusions: More than half of the nursing students had a moderate level of nomophobia. There is a relationship between the purpose of smartphone use and students’ personality traits with their nomophobia levels.