Background <p>Ultra-processed food (UPF) consumption and night eating behavior are increasingly common in modern dietary patterns and may negatively affect sleep quality. While each factor has been independently associated with adverse health outcomes, their combined influence on sleep-related well-being is less understood.</p> Methods <p>This cross-sectional study included 1111 adults aged 18–65 years from Türkiye. Data were collected using a structured online questionnaire, including the Screening Questionnaire for Highly Processed Food Consumption (sQ-HPF), Night Eating Questionnaire (NEQ), and Pittsburgh Sleep Quality Index (PSQI). Pearson correlation, multiple linear regression, and binary logistic regression analyses were conducted to explore the associations between UPF intake, night eating behavior, and sleep quality.</p> Results <p>UPF intake was positively correlated with both night eating (<i>r</i> = 0.288, <i>P</i> &lt; 0.001) and PSQI scores (<i>r</i> = 0.216, <i>P</i> &lt; 0.001). Night eating was also positively associated with poorer sleep quality (<i>r</i> = 0.285, <i>p</i> &lt; 0.001). Regression analyses showed that age, marital status, number of meals and snacks, NEQ scores, and PSQI scores were independently associated with UPF intake. NEQ and UPF scores were also independently associated with poor sleep quality.</p> Conclusion <p>UPF consumption and night eating behavior appear to be important behavioral factors associated with reduced sleep quality. Interventions targeting these dietary behaviors may contribute not only to improved sleep health but also to enhanced overall quality of life in adults.</p>