HEAVY metal pollution is widespread worldwide, threatening global food security. An experiment was conducted on wheat (Triticum asetivum L.) to evaluate the hazard impacts of lead (Pb) and nickel (Ni) stresses and the mitigating role of Sonchus oleraceus (S) extract as a grain priming application. It was revealed that the growth traits of wheat plants (e.g., including lengths, fresh and dry masses of root and shoot, leaf area, and yield attributes) were significantly reduced by 100mM Pb or Ni. Chlorophylls, total pigments, and photosynthetic activity (Fv/Fm) declined, although carotenoids increased significantly. Ni stress had the highest reduction compared to the control. Moreover, the endogenous status of phytohormones and the chemical composition of the yielded grains were modified by Pb and Ni in a different pattern, indicating that wheat had varying tolerance responses to different heavy metals. The beneficial components of S that support its promising alleviating role were exhibited in an analysis of extracts. Most wheat metabolic activities were restored by the S priming, with additional significant enhancements in growth criteria, photosynthetic parameters, and crop yield productivity. The accumulation of heavy metals in the produced grains was limited by priming with S extract, with an additional enhancement in their nutritional value. The phytohormonal balance was retrieved after grain priming with the S extract. Therefore, using natural S extract as a simple priming application could be a sustainable and safe method to alleviate the adverse effects of Pb and Ni stress on wheat productivity.