Bush called Gonzales "a man of integrity, decency and principle" who played "a critical role" in rooting out potential terrorists to make life safer for Americans.
Bush stood steadfast and loyal behind his former chief counsel even as leaders from both parties called for his resignation amid allegations of politicizing the Justice Department, perjury and civil rights violations.
"After months of unfair treatment that has created harmful -- a harmful distraction at the Justice Department, Judge Gonzales decided to resign his position and I accepted his decision," Bush said.
He went on to lambaste critics for dragging Gonzales' "good name through the mud for political reasons."
Solicitor General Paul Clement will become acting attorney general starting Sept. 17, Bush said without revealing whom he planned to nominate for the permanent spot.