Piano learning motivation is positioned as an important determinant of student’s success in music education, influencing the quality and engagement of practice. Different types of motivation impact students’ engagement levels, yet the relationship between motivation and the quality and engagement of practice remains underexplored in the literature. This study examined the correlations between various types of motivational regulation and students’ practice quality and engagement and provided an in-depth exploration of what drives undergraduate piano students to practice. Grounded in Self-Determination Theory (Deci & Ryan, 1985) and Organismic Integration Theory (Ryan & Deci, 2000), the study adopted Hallam’s (Hallam, 2013; Hallam et al., 2021) framework of music practice to assess motivation in relation to practice. A mixed-methods approach was employed, involving 160 undergraduate piano students from public universities in mainland China who completed a self-reported survey, 27 of them also participated in follow-up semi-structured interviews. Quantitative findings revealed a strong positive relationship between autonomous motivation and practice quality and engagement. Interview data further highlighted the significance of diverse motivational factors in shaping students’ learning experiences. These findings contribute to a deeper understanding of the role of motivation in undergraduate piano education, extending existing literature on music learning in the context of piano study. This research also provides practical implications for piano instructors, emphasizing the need to foster a more autonomy-supportive learning environment to enhance students’ engagement, motivation, and long-term musical development.