Background/Objectives: A proper posture is essential for musculoskeletal health, and a poor posture can lead to low back pain. To address the limitations of traditional text-based questionnaires, this study developed and validated a visualized posture assessment questionnaire for evaluating daily postures related to low back pain. The questionnaire was administered in Taiwan and designed using Traditional Chinese language. Methods: The proposed questionnaire evaluates six categories of daily activities including lifting heavy objects, sitting, putting on shoes, face washing and tooth brushing, getting out of bed, and doing sit-ups, or similar actions. Each category comprises an ergonomic posture and a non-ergonomic posture with corresponding illustrations. The questionnaire was administered to 100 participants, and its internal consistency was evaluated using Cronbach’s α, while test–retest reliability was assessed using intraclass correlation coefficients (ICCs). An expert panel reviewed the content validity, and the item-level content validity index (I-CVI) was calculated for each item and illustration. Results: Testing revealed a Cronbach’s α of 0.808, indicating high internal consistency, and a test–retest reliability, as measured by ICCs, of 0.78, indicating high stability over time. The I-CVI scores were high across all items, with the illustrations unanimously rated by the experts as highly relevant, supporting the effectiveness of the questionnaire’s visualized format for enhanced comprehension. Conclusions: The proposed questionnaire exhibits high reliability and validity, rendering it effective in evaluating posture-related risks of low back pain. This questionnaire also offers a more accessible and intuitive alternative to text-based questionnaires, with potential applications in clinical and research settings.