"I want to offer apologies to all victims affected by these sins and crimes," Bishop Francis Kane said during the news conference.
The documents include complaints, personnel files and more and are expected to identify 30 former clergy members accused of abusing children, and the church officials who help protect the accused. They are being released as part of a legal settlement.
The archdiocese says 95 percent of the incidents in these cases, all of which were reported to the police, occurred prior to 1988.
For years, victims of sexual abuse have been fighting for this day to come.
"It's still really painful at times," said Joe Iacono, abuse victim.
Iacono gets emotional when he thinks about the abuse he says he suffered at the hands of a priest when he was 11 years old.
"As a child when this abuse took place, no one can ever convince me they didn't know he was an abusive priest because they moved him in the middle of night and they did it seven times," said Iacono.
The Archdiocese of Chicago is the nation's third-largest archdiocese. Last Sunday, Francis Cardinal George released a letter to Chicago-area parishioners informing them of Wednesday's release. He said he wrote the letter to be accountable and transparent.
"It's always important to tell the truth. Since the publications of dozens of events that happened in the 80s before I got here is going to be, nonetheless, the occasion for a lot of conversation, I thought I better put it in some perspective. So, that was the purpose of the letter," he said Sunday.
"It's just a dishonest letter. It's a disingenuous letter," said Kate Bochte of the Survivors Network of those Abused by Priests, or SNAP.
Other SNAP members said the letter was not where parishioners and the public would find the truth about what happened.
"You'll get the truth from the victims and survivors and the witnesses -- not from clergy members who are only out to protect themselves from accountability.
Wednesday's document release did not include anything on Fr. Daniel McCormack, the only priest to commit any abuse under Cardinal George's tenure. Lawyers say those documents are currently sealed because of pending litigation.
The documents handed over Wednesday will be made public next week, once some information has been redacted.