Health-related quality of life (HRQoL) is a comprehensive measure that evaluates an individual’s well-being across physical, mental, and social dimensions. Enhancing HRQoL, particularly in individuals with chronic conditions like inflammatory bowel diseases (IBD), necessitates a holistic approach. Mindfulness, a scientifically supported strategy for managing anxiety, has shown promise in improving both physical and mental health. Its benefits may be partly explained through its effects on the gut–brain axis (GBA), a bidirectional communication link between the gastrointestinal system and the central nervous system. By exploring the interplay between mindfulness and the GBA, this study aims to uncover how these elements collectively influence HRQoL in both healthy individuals and those with IBD, offering insights into potential therapeutic pathways. A cross-sectional investigation involved 338 adults, including 50 IBD patients, utilizing validated Greek scales for Mindfulness (MAAS-15), Mediterranean Diet (14-MEDAS), and HRQoL (EQ-5D-5L). The questionnaire gathered demographic, anthropometric, and lifestyle data. Among healthy participants, EQ-5D-5L showed a moderate correlation with the MAAS-15 scale (r = 0.389, p < 0.05) and a low correlation with 14-MEDAS (r = 0.131, p < 0.05). IBD patients exhibited significantly lower mean EQ-5D-5L scores than healthy individuals (0.75 vs. 0.85, p < 0.05). MAAS-15 demonstrated a robust correlation (r = 0.414, p < 0.001) with EQ-5D-5L in IBD patients. Elevated mindfulness levels emerged as predictive factors for higher HRQoL in IBD patients (OR: 1.101, 95% CI: 1.008, 1.202, p < 0.05, compared to low mindfulness). In summary, factors influencing the GBA, including mindfulness and the Mediterranean diet, exhibit positive associations with HRQoL. Increased mindfulness levels predict better HRQoL in IBD patients, emphasizing the potential for clinical trials to validate these cross-sectional study findings.