Biochar seems to be a very promising material for remediation, reducing heavy metal mobility in contaminated sites. However, the effect of its application on soil depends on biochar origin, pyrolysis condition, soil type and properties like initial pH or cation exchange capacity, and also on metal form and interactions. This makes prediction about successful remediation with biochar more difficult and a lot of attention should be paid to choose the proper material appropriate to soil conditions. The aim of our study was to evaluate wheat straw biochar application on multi-contaminated soil, to decrease their mobility and minimize the risk of heavy metal occurrence in the area impacted by copper smelting processes. The results of this study indicate that wheat straw biochar application can potentially reduce Cu, Pb, Zn or Cd mobility only in sandy or acidified soils due to the liming effect. In alkaline soils the effect of biochar application on metal immobilization was imperceptible. The effect of wheat straw biochar on heavy metal immobilization in multi-contaminated soils is more complex and cannot be defined as all-purpose material in remediation procedures.