Climate change has promoted the expansion of viticulture toward southern Chile. However, in regions like La Araucanía, low heat accumulation and high rainfall often limit ripening and phenolic development in Vitis vinifera L. grapes. To address this, the use of reflective ground films has been proposed to enhance light interception by the canopy. This study evaluated the effect of reflective ground film on the technological and phenolic quality of cv. ‘Pinot Noir’ grapes. The trial was conducted using three treatments: (1) control without film, (2) reflective ground film installed at the onset of veraison (FV), and (3) reflective ground film installed at 80% veraison (F80V). A randomized complete block design with four replicates per treatment was used. At harvest, total soluble solids (TSS), total acidity, pH, yield, total phenols, and anthocyanins were measured. The FV treatment increased reflected light by up to 60% and significantly enhanced TSS (7.3%), total phenols (7.2%), and anthocyanins (69.3%) compared to the control. No significant differences were observed in acidity, pH, or yield. The results indicate that installing reflective ground film at veraison improves ripening and phenolic accumulation in cold climate vineyards.