The C2H2-type zinc finger proteins play crucial roles in various developmental processes and environmental stress tolerance in plants. Zinc Finger of Arabidopsis Thaliana11 (ZAT11), has been previously reported as an active repressor. We show here that GFP-tagged ZAT11 is targeted to the nucleus. Transgenic plants overexpressing ZAT11 show enhanced primary root growth. Analysis of β-glucuronidase (GUS) expression in transgenic plants expressing a ZAT11 promoter–GUS reporter chimeric gene confirmed that ZAT11 was expressed in roots and its expression was particularly high in root tips. ZAT11-overexpressing transgenic plants were specifically sensitive to nickel ions (Ni2+). Transcript levels of a tonoplast-localized Ni2+ transporter gene, IREG2, were approximately 2-fold decreased in transgenic plants overexpressing ZAT11 and this correlated with a reduced capacity for Ni2+ accumulation in their roots. Altogether, our results reveal that ZAT11 functions as a positive regulator of primary root growth but a negative regulator of Ni2+ tolerance, suggesting a novel biological function of Arabidopsis C2H2-type zinc finger protein in metal detoxification.