The herbicide "fomesafen" causes phytotoxicity to the rotational wheat crop and may reduce its yield. Considering that biochar may improve remediation and biophysical conditions of the contaminated soil environments to benefit plant growth. Here, we investigated the impacts of three levels of the wheat straw-derived biochar (1%, 2%, and 4% (w/w)) on growth, physiological properties, and rhizosphere microbial communities of the wheat (Triticum aestivum) seedlings under the fomesafen stress using high-throughput sequencing. The results showed that biochar amended into soil significantly reduced the uptake of wheat to fomesafen and thereby eliminate its toxicity to wheat seedlings. Moreover, biochar increased the abundance and diversity of plant beneficial bacterial and fungal taxa in the rhizosphere of wheat seedlings. Compared with the three addition amounts, amendment with 2% of biochar has the best effects to reduce the toxicity of fomesafen on wheat seedlings and maintain the balance of soil microbial community structure in soil contaminated with fomesafen (1.0 mg kg-1). Overall, our results suggest that the level of biochar application influences the structure and diversity of soil microbiome (and mycobiome) and plant performance under abiotic stress conditions.