Tujuan penelitian dan pengembangan ini adalah untuk mengembangkan multimedia pembelajaran berbasis Learning Trajectory untuk meningkatkan kemampuan pemecahan masalah matematika pada siswa kelas IV SD. Metode penelitian yang digunakan adalah metode research and development (R&D dengan menggunakan model penelitian ADDIE. Adapun model pengembangan ADDIE memiliki tahapan yaitu 1) Analis, 2) Desain, 3) Development, 4) Implementation, and 5) Evaluation. Lokasi penelitian ini dilakukan di SDN Selosari II Kabupaten Kediri dengan jumlah subjek coba siswa kelas IV SD sebanyak 29 orang siswa. Data yang digunakan untuk melihat kelayakan produk produk yaitu data terkait kevalidan, kepraktisan dan keefektifan. Instrumen penelitian yang digunakan berupa lembar observasi, angket validasi ahli, angket respon guru dan tes hasil belajar. Hasil analisis data tingkat kevalidan produk berdasarkan hasil penilaian ahli media pembelajaran dan ahli materi matematika SD menunjukkan rata-rata skor 86,75% dengan kriteria sangat valid. Hasil analisis data uji kepraktisan produk berdasarkan angkat respon guru mendapat skor 90% dengan kriteria sangat praktis. Sedangkan hasil analisis data terkait uji keefektifan produk yang dilihat dari hasil belajar siswa memperoleh nilai rata-rata klasikal 81,5 dengan kriteria efektif. Berdasarkan hasil analisis data yang telah dilakukan dapat disimpulkan bahwa multimedia pembelajaran berbasis Learning Trajectory layak digunakan untuk meningkatkan kemampuan pemecahan masalah matematika pada siswa kelas IV SD. Multimedia learning based on learning trajectory to improve the mathematical problem-solving abilities of Class IV elementary school students Abstract: This research and development aims to develop Learning Trajectory-based multimedia learning to improve mathematical problem-solving abilities in fourth-grade elementary school students. The research and development method (R&D using the ADDIE research model) is used. The ADDIE development model has stages, namely Analysis, Design, Development, Implementation, and Evaluation. The location of this research was carried out at Selosari II Elementary School, Kediri Regency, with a total of 29 elementary school fourth-grade students as test subjects. The data used to see the suitability of the product is data related to validity, practicality, and effectiveness. The research instruments used were observation sheets, expert validation questionnaires, teacher response questionnaires, and learning outcomes tests. The results of data analysis on product validity levels based on the assessment results of learning media experts and elementary school mathematics material experts show an average score of 86.75% with very valid criteria. The results of product practicality test data analysis based on teacher responses received a score of 90% with very practical criteria. Meanwhile, the results of data analysis related to product effectiveness testing, as seen from student learning outcomes, obtained a classical average score of 81.5 with effective criteria. Based on the results of the data analysis that has been carried out, it can be concluded that Learning Trajectory-based multimedia learning is suitable for improving mathematical problem-solving abilities in fourth-grade elementary school students.