This study introduces a Human–AI Co-Creation Design (HACD) Framework aimed at enhancing customer experience in the packaging design of traditional cultural products. Although artificial intelligence (AI) is increasingly recognized as a creative partner in design, limited research has quantitatively explored how human–AI collaboration affects aesthetic perception, cultural engagement, and emotional experience. To address this gap, the study integrates insights from design semiotics, co-creation theory, and emotional design to develop a structural model comprising six key constructs: AI–Human Synergy (AHS), Cultural Symbol Integration (CSI), Design Aesthetic Consistency (DAC), Emotional Resonance (ER), Perceived Cultural Value (PCV), and Customer Experience (CX). A quantitative survey was conducted with 250 consumers familiar with Chinese cultural products, and hypotheses were tested using Structural Equation Modelling (SEM). The results indicate that AI–Human synergy significantly enhances design aesthetic consistency, while cultural symbol integration strengthens emotional resonance. Additionally, perceived cultural value emerged as a strong predictor of customer experience, with emotional resonance mediating the relationship between design aesthetics and cultural value. The study extends co-creation theory by positioning AI as an active participant in cultural design and provides empirical support for combining cultural semiotics with computational creativity. Practically, the HACD framework offers actionable guidance for packaging designers aiming to balance cultural authenticity with AI-driven innovation. Overall, the findings suggest that human–AI co-creation does not replace human creativity but evolves it toward intelligent cultural design, where tradition and technology collaboratively produce meaningful and emotionally engaging design experiences.