This research was motivated by the suboptimal use of digital teaching materials that can accommodate the diverse characteristics of students, as well as students’ low mathematical problem-solving skills and self-efficacy in learning One-Variable Linear Equations (OVLE). This study aimed to develop a differentiated Electronic Student Worksheet (E-LKPD) based on Realistic Mathematics Education (RME) and to analyze its validity, practicality, and effectiveness in improving students’ mathematical problem-solving skills and self-efficacy. The study employed a Research and Development (R&D) method using the ADDIE model, which consists of analysis, design, development, implementation, and evaluation. The trial subjects consisted of 90 students and 3 teachers in the needs analysis stage, 1 teacher in the individual trial, 9 students in the small-group trial, and 30 seventh-grade students from Class VII-C in the field trial at SMP IT Darur Rasyid. Data were collected through expert validation, questionnaires, observations, and pretest-posttest assessments. The results showed that the validity of the E-LKPD reached 77.5% according to the material expert and 92.5% according to the design expert. The practicality of the product reached 87.5% in the individual trial and 80% in both the small-group and field trials. The effectiveness analysis based on the N-Gain scores indicated an improvement of 85.6% in students’ mathematical problem-solving skills and 83.3% in self-efficacy, both of which were categorized as effective. Therefore, the differentiated E-LKPD based on RME was declared valid, practical, and effective for use in learning One-Variable Linear Equations.