ING proteins are tumor suppressors involved in the regulation of gene transcription, cell cycle arrest, apoptosis, and senescence. Here, we show that ING1b expression is upregulated by several DNA-damaging agents, in a p53-independent manner. ING1b stimulates DNA repair of a variety of DNA lesions requiring activation of multiple DNA repair pathways. Moreover, Ing1(-/-) cells showed impaired genomic DNA repair after H2O2 and neocarzinostatin treatment and this defect was reverted by overexpression of ING1b. Two tumor-derived ING1 mutants failed to promote DNA repair highlighting the physiological importance of the integrity of the PHD domain for ING1b DNA repair activity and suggesting a role in the prevention of tumor progression. Ing(-/-) cells showed higher basal levels of γ-H2AX and, upon DNA damage, γ-H2AX increase was greater and with faster kinetics compared to wild-type cells. Chromatin relaxation by Trichostatin A led to an exacerbated damage signal in both types of cells, but this effect was dependent on Ing1 status, and more pronounced in wild-type cells. Our results suggest that ING1 acts at early stages of the DNA damage response activating a variety of repair mechanisms and that this function of ING1 is targeted in tumors.