Sunflower (Helianthus annuus L.) is a type of annual plant that belongs to the Asteraceae family. However, various kinds of abiotic stresses, especially metal toxicity (Cd), substantially reduce its growth. The frequent release of mine and industrial wastewater as well as the overuse of chemical fertilizers are the main causes of this hazardous metal’s rising proliferation. At the same time, even though plants have a robust defense against Cd toxicity, they are unable to combat greater levels of the metal’s toxicity. Meanwhile, it has been demonstrated that applying zinc can significantly reduce the hazardous effects of cadmium. Therefore, the present experiment aimed to investigate the positive impacts of Zn application (0, 50, and 100 ppm) on the sunflower variety “FH-516” to combat Cd stress as an eco-friendly approach. Heavy metal (Cd) toxicity curtailed the root length, shoot length, leaf area, chlorophyll a/b ratio, 100-seed weight, and biological yield up to 32.03%, 27.03%, 26.1%, 31.33%, 34.46%, and 22.37%, respectively. Exogenous application of zinc significantly improved the Cd-induced losses and increased the root length (37.9%), shoot length (48.4%), leaf area (56.2%), chlorophyll a/b ratio (65.64%), 100-seed weight (66.98%), and biological yield (74.04%). Mineral ions, e.g., Na+, of root and shoot (61.02% and 29.42%) increased under Cd stress, whereas K+ and Ca2+ decreased due to Cd toxicity in both root and shoot. Generally, the application of zinc improved the polyphenolic compounds and ion contents of plants under stressed conditions. At the same time, the application of Zn (100 ppm level as compared to 50) substantially increased the flavonoid contents up to 92.92% as compared to anthocyanin contents of 52.11% in Cd-stressed plants. Current findings reveal that using zinc could be an effective strategy against abiotic stresses and could be suggested for the decontamination of mild to moderately contaminated soils containing Cd.