The present study investigated the copper tolerance and bioremediation potential of endophytic bacteria because endophytic bacteria are the most common bacterial strains associated with heavy metal bioremediation. The acute toxic effects of copper on living organisms were determined using two endophytic bacterial species, Bacillus sp. and Streptomyces griseus (S. griseus). After 4 days of acute toxicity test, changes in metal and bacteria concentrations in water, inhibition (%), bioaccumulation rate, and bioconcentration factors were evaluated. According to the evaluations, cell weights decreased, and inhibition rate (%) increased with increasing metal concentration after a certain level (10 mg/L Cu). With increasing metal concentrations from 5 to 25 mg/L, biosorption efficiency decreased from 35.94% to 20.73% for S. griseus and from 56.36% to 34.47% for Bacillus sp. The bioaccumulation quantities increased with increasing metal concentrations for both species. Based on the present findings, it is concluded that Bacillus sp. and S. griseus are suitable candidates for the bioremediation of copper ions from contaminated environments. These endophytic bacteria use hyperaccumulating plants for more effective bioremediation of heavy metals.