Firstly, three solid wine wastes (stalks, seeds and peels) and a commercial tannin powder (T), rich in polyphenols, have been added (6% wt) into PP matrix by melt mixing. Thermal and mechanical properties of these new materials have been investigated by means of Different Scanning Calorimetry (DSC), tensile test, Dynamic Mechanical Analysis (DMA) and creep tests. The short-term stability has been evaluated by Oxidation Induction Time (OIT), Oxidative Onset Temperature (OOT) and thermogravimetric analysis (TGA). Each test has underlined the wine additives ability to enhance the PP short-term thermal stability. Finally, the creep resistance has been improved by the wine additives. Subsequently, wine seeds (Se) and their polyphenolic extract (Sext) have been tested as long-term stabilizers against both UV and heat aging agents. The results have been compared with the ones obtained using both the classical PP stabilizer (Irganox 1010) and again the additive T. PP-based films have been aged by UV and the C=O formation has been monitored during the aging time in order to build up the long-term OIT curves. PP based specimens have been oven aged at 110 °C and tensile properties have been monitored during the aging time. The effect of the oven aging has been evaluated also by Melt Flow Index (MFI) measures and by DSC. In both UV and oven aging tests, results have evidenced the ability of each wine derived additive to work as long-term stabilizers. In particular, the polyphenol seed extract (Sext) has exhibited the best OIT values and the lowest elongation at break loss, resulting even better than Irganox 1010 and commercial extract T. These results combined with the wine additives investigation (by FT-IR), have given to the polyphenols quality the PP stabilization key-role. These results show that winemaking by-products display promising potentials as possible alternatives to conventional synthetic polymer additives, with an environmentally and cost-effective advantage.