The impact of chelating agents and external activators, particularly tartaric acid and Methyl Jasmonate, on cadmium (Cd) accumulation in sunflowers was examined to improve the efficacy of sunflower-based remediation in Cd-polluted soil. Utilizing sunflowers as the experimental model, a pot experiment was conducted to evaluate the effects of the chelating agent EGTA alongside tartaric acid (TA) and Methyl Jasmonate (MeJA) on various parameters, including plant height, dry weight of both root and shoot systems, Cd uptake, and the rate of soil Cd extraction. The findings revealed that the application of TA or MeJA alone significantly enhanced sunflower growth, resulting in biomass increases of 18.85% and 5.28%, respectively, compared to the control group. Conversely, the use of EGTA alone suppressed growth, causing a biomass reduction of 23.13%. The individual and combined effects of EGTA with external activators on Cd concentration and accumulation across different parts of the sunflower plant exhibited variability. Notably, the individual applications of EGTA, TA, and the combination of EGTA with TA and MeJA considerably elevated Cd concentration and accumulation in sunflowers relative to the control. The most significant effects were observed with the combination of EGTA and 1.25 mmol/kg of TA, which produced increases in Cd concentration of 96.48%, 86.86%, and 502.19% in the roots, stems, and leaves, respectively, leading to an overall increase in Cd accumulation in the entire sunflower plant of 328.54% compared to the control. Moreover, the application of EGTA and external activators affected the Cd transport coefficients in different sunflower organs, with EGTA, TA alone, and the combination of EGTA with TA and MeJA enhancing the efficiency of Cd extraction from the soil. The highest extraction efficiency, reaching 1.15%, was achieved with the combination of EGTA and 1.25 mmol/kg of TA. These results suggest that the integration of external activators with chelating agents in the remediation of Cd-contaminated soil significantly boosts the ability of sunflowers to accumulate and remove Cd.