<p>Increasing heavy metals (HMs) in vegetables irrigated with effluents, like landfill leachate (LL), necessitate strategies to reduce their accumulation and associated health risks. This study aimed to investigate the effects of zeolite and biochar (2% w/w) on the morphological characteristics of lettuce, the uptake of HMs, including cadmium (Cd), lead (Pb), nickel (Ni), and zinc (Zn), and their health risk index (HRI) under irrigation with different LL concentrations (25%, 50%, 75%, and 100%). The results showed that increasing LL concentrations significantly decreased leaf area, root and shoot fresh and dry weights, and root and shoot lengths while increasing HMs in the soil, roots, and shoots of lettuce compared to the control. On the other hand, biochar, more efficient than zeolite, improved growth characteristics such as length, fresh weight, and dry weight in both roots and shoots. Additionally, biochar application reduced Pb and Cd levels in soil and plants. The maximum amount of reduction, were 20.2% and 40.9% in soil, 45.5% and 45% in roots, and 62.1% and 55.7% in shoots, respectively. This reduction in Pb and Cd brought the HRI values for both metals to safe levels (HRI &lt; 1) for both children and adults. On the contrary, zeolite showed a better function in reducing the transfer of Ni to roots and shoots. However, from the aspect of improving the morphological characteristics and decreasing the uptake of HMs, for the safe cultivation of vegetables irrigated with LL, the use of biochar was found to be more effective than zeolite.</p> Graphical Abstract <p></p>