<p>Students’ homework procrastination significantly affects the quality of homework completion, learning satisfaction, emotional responses to homework, and even academic performance and workload. Reducing homework procrastination is therefore critical for fostering students’ academic development and well-being. This study investigated the relationships between three distinct types of parental homework involvement—autonomy support, content support, and structure—and students’ homework procrastination. Additionally, the study examined the mediating role of homework motivation, specifically competence beliefs and subjective task value, as well as the moderating effect of parental education level and students’ grade level on these relationships. A total of 5394 elementary and middle school students (grades 3–8) participated in the study by completing validated survey measures. The findings revealed that: (1) parental autonomy support and content support were negatively associated with students’ homework procrastination, while the effect of parental structure on homework procrastination was not statistically significant; (2) competence belief and subjective task value partially mediated the relationships between parental autonomy support, structure, and students’ homework procrastination. However, although competence belief mediated the link between parental content support and homework procrastination, subjective task value did not significantly mediate this relationship; (3) parental education level moderated several relationships among quality of parental homework involvement, homework motivation, and students’ homework procrastination and (4) students’ grade level moderated the relationship between parental content support and students’ homework procrastination. These findings provide important implications for parental strategies to enhance homework-related motivation, foster effective home-school collaboration, and mitigate students’ tendencies toward homework procrastination.</p>