In order to evaluate the risks of heavy metals contamination, it is essential to understand their bioavailability which depends on their form in the soil, rather than on the total amount accumulated. The conditions at the root–soil interface, often referred to as the rhizosphere, are considerably different from those existing some distance from the root system. On the other hand, the complexity of the soil–plant relationship may induce changes in the properties of the soil rhizosphere and consequentially the metal fractionation in it. Studies dealing with plant-induced changes in heavy metals fractionation in the rhizosphere soil sometimes produce different results. However, temporal changes in metal fractionation during plant growth may provide another reasonable explanation. The primary objective of this study was to investigate Zn, Pb, Cu, Ni, Cr and Co fractionation in the soil in an attempt to obtain a better understanding of their availability and subsequent uptake by maize and sunflower. In this regard, the study focused on root-induced changes of various fractions of Zn, Pb, Cu, Ni, Cr and Co in the maize and sunflower rhizosphere. Plants were seeded in a rhizobox, a box that is consisted of four parts constructed from polyvinyl chloride mesh. The devices were cultivated for 21, 42, and 63 days for maize and sunflower and 84 days only for maize. At the termination of the cultivation period, maize and sunflower plants were harvested and soil samples were collected. For fractionation of heavy metals, the soil samples were sequentially extracted using an operationally defined sequential fractionation procedure. The total organic carbon (TOC) in the soil and the DOC in the soil solution were determined using a TOC analyzer. The results demonstrated that there were continuous changes in heavy metals fractionation within the maize and sunflower rhizosphere. Initially, the amount of exchangeable fraction increased before dropping below the initial level after 42 days or so. The exchangeable fraction of Cu and Zn in the soil rhizosphere did not further increase after 21 days, While the exchangable fraction of Ni further increased after 63 days. Carbonate associated Zn, Cu, and Ni followed a similar trend of change, but with a slower rate than the exchangeable fractions. There were also initial increases in oxide bound copper followed by a turnover after 40–50 days, but in the case of Zn, from the beginning until the end of planting this fraction showed continuous increase. Metal fraction bound to organic mater for most metals studied increased significantly at the 63 days after planting. Changes in the organic fraction in distance from both plant’s root for the most of heavy metals in study was significant, and the rhizosphere and bulk soil have maximum and minimum concentration of organic fraction, respectively. Unlike the organic