<p>Studies on the impact of mycorrhizae on tree seedlings’ establishment in rebuilt fragile forest ecosystems disturbed by industrial activities remain insufficiently reported. Oil sands mining in Alberta, Canada has resulted in a large-scale land disturbance of the boreal forest and produced large amounts of phytotoxic tailings. To accelerate the tailings solidification and mitigate the environmental harm to local forest ecosystems, oil sands operators have developed the novel tailings technology referred to as enhanced non-segregating tailings (eNST) and enhanced-spiked non-segregating tailings (esNST). In this study, we investigated the effect of ectomycorrhiza <i>Laccaria bicolor</i> inoculation on growth responses of two keystone boreal species, jack pine (<i>Pinus banksiana</i>) and white spruce (<i>Picea glauca</i>) seedlings to eNST and esNST treatments in a controlled-environment growth chamber. Seedlings were grown for eight weeks in five substrates: peat-mineral soil mix (PMM), PMM with eNST, PMM with esNST, eNST alone, and esNST alone. From analysis of variance (ANOVA) and post hoc tests of the data, we found that the growth of jack pine and white spruce was severely impaired by eNST and esNST, with significant reductions in chlorophyll concentration, net photosynthesis, and total dry weights. Jack pine was more sensitive to tailings compared with white spruce and exhibited greater growth reductions than white spruce. Inoculation with <i>L. bicolor</i> enhanced plant tolerance to tailings, reduced concentrations of B in needles of jack pine seedlings treated with eNST, and concentrations of B and Na in needles of white spruce seedlings treated with eNST and esNST. The findings from this study demonstrate the importance of mycorrhizal associations for plants in reclamation areas affected by phytotoxic tailings and their potential for improving revegetation success.</p>