Latar Belakang: Pertumbuhan dan perkembangan balita merupakan aspek penting yang berpengaruh terhadap kualitas kehidupan seorang anak di masa mendatang. Meskipun akses terhadap fasilitas kesehatan cukup baik, ibu yang memiliki pengetahuan rendah cenderung kurang terlibat dalam memantau perkembangan anak secara aktif. Kesenjangan ini menunjukkan perlunya intervensi yang berfokus pada peningkatan pengetahuan ibu tentang pentingnya pemantauan perkembangan balita. Tujuan penelitian ini untuk mengetahui hubungan antara tingkat pengetahuan ibu tentang pemantauan perkembangan balita dengan perkembangan balita. Metode: Penelitian ini menggunakan rancangan deskriptif operasional dengan pendekatan cross-sectional. Penelitian dilakukan di Pustu Cemagi, UPTD Puskesmas Mengwi II Kabupaten Badung pada bulan Juni 2025. Sampel penelitian adalah ibu yang mempunyai balita di Pustu Cemagi. Pengambilan sampel menggunakan metode non-probability sampling dengan teknik pusposive sampling. Analisa data menggunakan uji statistik chi-square. Hasil: Dari 180 ibu yang menjadi responden, 103 ibu (57,2%) berpengetahuan baik dan 77 orang (42,8%) cukup. 150 (83,3%) balita perkembangannya sesuai umurnya. Terdapat hubungan bermakna antara tingkat pengetahuan ibu tentang pemantauan perkembangan balita dengan perkembangan balita (p-value

Background: The development and growth of toddlers are essential aspects that significantly affect a child's future quality of life. Despite favourable access to healthcare facilities, mothers with low levels of knowledge tend to be less actively involved in monitoring their children's development. This gap highlights the necessity for interventions focused on enhancing mothers' understanding of the importance of monitoring toddler development. Purpose: To determine the correlation between the level of mothers' knowledge about monitoring toddler development and toddler development in the working area of the Cemagi public health center. Method: This study employed a descriptive operational design with a crosssectional approach. The study was conducted at the Cemagi Public Health Centre of Mengwi II, Badung Regency, in June 2025. The sample of this study consisted of mothers with infants at the Cemagi Public Health Centre, which was conducted using non-probability sampling with a purposive sampling technique. Data analysis was performed using the chi-square statistical test. Result: The findings showed that 103 mothers (57.2%) had good knowledge and 77 (42.8%) had sufficient knowledge. There were 150 (83.3%) toddlers developed according to their age. There was a significant correlation between the level of mothers' knowledge of infant development monitoring and infant development (pvalue < 0.05). Conclusion: The level of mothers' knowledge is related to infant development. It is expected that all mothers will have adequate knowledge and improve their quality of life in order to optimally support their children's development. Keywords: Knowledge of Mother, Development, Toddlers