<p> Purpose Heavy metal absorption causes adverse effects on the growth and yield of canola. The study’s objective was to elucidate the mechanism by which glycine betaine can improve canola’s resistance to nickel toxicity, offering crucial information to promote the growth of sustainable agriculture. Methods The treatments of the experiment were a). Nickel tress levels, Ni0 = control, Ni1 50&#xa0;mg kg^− 1, and Ni2 100&#xa0;mg kg^− 1, b). Glycine betaine (0, 10 mM) concentrations and c). Canola varieties (AARI and Super). Results Nickel stress decreased the root length up to (22.5 and 37.5%), shoot length (22.7 and 42.6%), total chlorophyll (20.5 and 22.7%), no. of seeds per siliques (31.4 and 38.7%) and 1000 grain weight up to (27.3 and 36.6%) among both varieties (V₁ and V₂), subsequently. The results on the application of glycine betaine (10 mM) showed an increase in root length (13.9 and 26.6%), shoot length (13.8 and 29.2%), total chlorophyll (12.8 and 13.1%), activity of glycine betaine (33 and 36.9%), and enzymatic antioxidants i.e. catalase (CAT) (69.9 and 43.7%), peroxidase (POD) (57.6 and 35.4%) and superoxide dismutase (SOD) (81.1 and 48.9%) were further increased whereas, reduced the oxidative activities of hydrogen peroide (H₂O₂) (13.5 and 13.3%) and malondialdehyde (MDA) up to (20.1 and 20.5%) in V₁ and V₂, respectively. Conclusion The present study identifies the promising value of glycine betaine in alleviating nickel-induced stress in canola, and it may provide a convenient and affordable means towards enhancing crop quality and yield in nickel-polluted soils, especially in industrial or even mining-related agricultural sites.</p> Graphical Abstract <p>A schematic diagram shows two different mechanisms of canola plants under nickel stress with foliar application of glycine betaine (GB). Catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), potassium (K⁺), calcium (Ca²⁺), sodium (Na⁺), nickel (Ni)</p> <p></p>