A novel, sustainable time-temperature indicator (TTI) ink based on natural pigments is introduced for food freshness monitoring. The ink, composed of hydroxyethyl cellulose (HEC), Clitoria ternatea anthocyanin, and N-hydroxyphthalimide (NHPI), was applied to art paper using screen printing. The inks were characterized through FT-IR, particle size analysis, and rheological measurements, with optimal performance achieved at Clitoria ternatea anthocyanin to NHPI ratios of 9:1 and 7:1. The color change of the ink followed the Arrhenius equation, correlating with food degradation activation energies ranging from 0 to 75 kJ/mol. The ink was applied to monitor pork freshness, demonstrating high sensitivity and accuracy in tracking food quality. This TTI ink offers a cost-effective, environmentally friendly solution for food freshness assessment, with potential applications in reducing food waste and enhancing consumer confidence in food safety.