His success - and the failure of predecessor, Cardinal Bernard Law - underscores the power individual Roman Catholic bishops have to determine how the abuse crisis plays out in their dioceses, even as they face pressure from insurers and their own attorneys.
"I've encountered more than half of the bishops in the United States over the past 20 years, and their attitude, personality and candor, and the variations in it, can dramatically affect how survivors are treated and how litigation is conducted - and even whether it's conducted," said Jeff Anderson, a Minneapolis attorney who specializes in sex abuse lawsuits.
Few examples equal that of Boston.
Law apologized repeatedly to victims, settled more than 80 lawsuits and removed dozens of accused priests from church work. But he appeared to take these actions reluctantly, and his history of sheltering some offenders irreparably damaged his credibility, church observers say.
He stepped down as Boston archbishop last December.
The day after O'Malley took over July 30, he revamped the legal team representing the archdiocese, hiring an attorney who had helped him settle abuse claims when he led the Diocese of Fall River, Massachusetts, a decade ago.
O'Malley was personally involved in the Boston negotiations, spending hours Sunday with victims' attorneys to reach the $85 million deal for 552 plaintiffs. Roderick MacLeish Jr., whose firm represents 260 victims, said the agreement announced Tuesday would not have been reached without "the efforts of a compassionate archbishop."
O'Malley played a similar role in Fall River, meeting with victims to help settle the cases there.
"He seems to be able to convey that openness in a way that Cardinal Law couldn't," said Philip Lawler, editor of Catholic World Report.
Lawler said he found Law "very easy to talk to, very solicitous of other people," but "in his case, the palace guard went into defensive mode. People didn't get through to him. It was access."
In the wake of the Boston settlement, some have predicted the deal will serve as a model for the nation's 194 other dioceses, many of which are facing lawsuits. However, the impact could be greatly limited by how each bishop responds to the outside pressures on him.
Insurers are sometimes the ones who choose a diocese's defense attorneys, and those lawyers may be more concerned with containing damage to the insurance company than preserving faith in the church.
When insurers are not involved, bishops are confronted with painful financial choices. Abuse lawsuits are not filed as class-action cases, which would set a time limit for plaintiffs to seek part of a settlement.
That makes it nearly impossible for dioceses to estimate the potential cost of lawsuits, especially in states where lawmakers have changed the statute of limitations on bringing such claims.
"It's very important who the bishop has as his lawyer," said the Rev. Thomas Reese, editor of the Jesuit magazine America.
Many bishops previously turned to attorneys with no expertise in abuse lawsuits and "they got some bad advice about stonewalling, which angered victims more and angered juries more," Reese said.
Still, some bishops have found ways to reach out to victims and parishioners, while effectively resolving their dioceses' legal problems.
The Diocese of Oakland, California, three years ago started a ministry that provides support for victims and educates clergy on preventing abuse.
Bishop Paul Bootkoski of Metuchen, New Jersey, was proclaimed "the model bishop in America" by the Survivors Network of Those Abused by Priests. Bootkoski has initiated contact with victims, personally met with them and apologized, while cooperating fully with prosecutors, SNAP said.
Archbishop Michael Sheehan took over the Archdiocese of Santa Fe, New Mexico, a decade ago as abuse claims against priests were mounting. He removed more than 20 accused priests, settled more than 200 molestation claims and promised to remove all abusive priests.
"Those bishops who reached out to the victims, talked to them, listened to them, have succeeded much better," Reese said. "By doing the right thing they did the correct thing legally and financially."
David Clohessy, national director of the Survivors Network, said bishops who help victims heal deserve praise, but he said the problem is broader than individual leaders.
"It's the culture of the organization," Clohessy said. "In any other organization, the personality of the CEO would play a more significant role. But this isn't any organization. It's a very old, traditional, rigid, hierarchical, unchanging institution."