Homework is an important factor in improving academic performance, but many students often struggle with consistent homework completion. The study had two objectives: (1) to study the impact of students’ attitudes toward homework on mathematics achievement and (2) to understand the driving factors that influence those attitudes. The study was conducted over a 10-week period at Boeung Salang Primary School in Phnom Penh, focusing on 26 Grade 5 “C” students. The study used a mixed-method design, collecting quantitative data on homework completion rates, attitude scores (surveys), and math test scores, and qualitative data from interviews. The study was based on the ABC model of behavior, which includes emotional, knowledge, and behavioral components, and Yadav’s (2017) theoretical framework on motivational factors for homework completion. Students’ attitudes toward homework were positively correlated with mathematics achievement (Multiple R = 0.68) and were statistically significant (p-value = 0.00014 < 0.05). This suggests that students’ positive attitudes may be an important influential variable in predicting academic performance. The β value = 0.0616 means that every 1 unit increase in attitude score will help increase the average math test score by 0.0616 points. In addition, R² = 0.4589 indicates that 45.89% of the variation in academic performance can be attributed to attitude variables. The study also found that factors that influence students’ attitude include parental support, teacher motivation, student self-responsibility, and peer relationships. These factors should be supported and developed regularly to foster a positive attitude towards learning. This research shows that students’ positive attitude towards homework has a strong impact on improving academic performance. Therefore, teachers should set meaningful homework that is appropriate for students’ abilities, provide timely feedback, and create a learning environment that encourages students to actively participate. These implications are of great value to educational institutions and teachers in promoting the quality of primary education and the development of students’ abilities in general. Key words: Attitude, Homework, Mathematic, Learning outcome, Simple Linear Regression