This study explores the valorization of olive pomace through the green recovery of bioactive phenolic compounds for application in active packaging for olive oil preservation, alongside the development of a low-cost analytical strategy aligned with white analytical chemistry principles. Ultrasound-assisted extraction using 50% (v/v) aqueous ethanol significantly improved polyphenol recovery, reducing extraction time to 2 min while increasing efficiency compared to conventional maceration. Total phenolic content was determined using the Folin–Ciocalteu method and measured with both a UV–Vis spectrophotometer and a portable 3D-printed smartphone-based device, which showed excellent agreement with the reference method and comparable analytical performance. Optimized extracts were incorporated into starch–glycerol films, enhancing UV-barrier properties and enabling controlled release of phenolics. When applied to olive oil packaging, the films reduced color degradation under accelerated aging, indicating improved photo-oxidative stability. Composting tests suggested the biodegradation capability of the developed materials under the evaluated conditions. Overall, the study demonstrates an integrated sustainable approach combining waste valorization, active packaging development, and accessible analytical innovation.