The application of polymers as an essential class of material was greatly inhibited due to the aging failure of these versatile materials during normal use. Hence, it is generally recognized that stabilization against thermo-oxidative aging is indispensable to extend the service life of polymers for long-term applications. However, toxicity and pollution of the state-of-the-art antiaging technologies have long been puzzles in the polymer industry. Herein, sustainable carbon nanodots (CDs), synthesized by facile and cost-effective microwave-assisted pyrolysis, are used for first time as radical scavengers to resist the thermo-oxidative aging of elastomers. We have demonstrated that incorporation of the resultant CDs could be green and generic radical scavengers toward highly aging-resistant elastomers. Furthermore, by controlling the photoluminescent quantum yield of the CDs with various passivated agents, tunable radical scavenging activity was achieved. We established for the first time that the aging resistance originates from the prominent reactive radical scavenging activity of the CDs, which was rationally controlled by their photoluminescent quantum yield.