Brown, a Democrat, and Acting DHS Secretary Chad Wolf spoke multiple times over the past 24 hours and agreed to a joint plan aimed at ending the unrest, which has caused tens of millions of dollars in damage and lost business to the downtown area.
State and local law enforcement will begin securing properties and streets, especially those surrounding federal properties like the Mark O. Hatfield Courthouse, Wolf said in a statement.
State police officers will work with officers from DHS's Federal Protective Service to make sure all federal properties are protected and secure.
"This plan is possible due to the valiant efforts of the DHS law enforcement officers protecting federal property in Portland from violent activity for the past two months," Wolf said.
Rioters in early July turned their attention from the Justice Center, a county building that houses a jail and a sheriff's office, to the federal courthouse, nearly overwhelming the officers there and prompting a surge in assets on July 4.
Federal officers erected a fence last week to keep the rioters away from the courthouse after they repeatedly set it on fire, pried wood panels away, and smashed windows.
Even with the new agreement, all federal forces currently in Portland will remain in place until it's clear the courthouse and other federal properties remain secure, Wolf said.
President Donald Trump told reporters outside the White House earlier in the day that "we're not leaving until they've secured their city."
"We told the governor, we told the mayor, secure your city. If they don't secure their city soon, we have no choice, we're going to have to go in and clean it out," he added.
Brown said that the federal government "agreed to withdraw federal officers from Portland," accusing them of acting "as an occupying force" and bringing violence to the city.
Starting Thursday, she said in a statement, all Customs and Border Protection and Immigration and Immigration and Customs Enforcement officers will leave downtown Portland.
"Our local Oregon State Police officers will be downtown to protect Oregonians' right to free speech and keep the peace. Let's center the Black Lives Matter movement's demands for racial justice and police accountability. It's time for bold action to reform police practices," Brown said.
Devin O’Malley, Vice President Mike Pence's secretary, said in a rebuttal that the vice president was "very clear that law & order must be restored in" Portland before federal law enforcement leaves.
Portland Mayor Ted Wheeler, a Democrat who also serves as police commissioner, said he appreciated Brown's willingness to use state resources to quell the unrest in his city.
State, county, and local law enforcement will only keep engaging if there is violent criminal activity, said Wheeler, who previously pushed a mix of appeasement and de-escalation that showed few signs of working.
The agreement represents a big shift from the gap between federal and state and local officials, who remained at odds throughout July. Oregon Attorney General Ellen Rosenblum, a Democrat, took the Trump administration to court to try to stop federal officers from making arrests, and Wheeler ordered local police to stop cooperating at all with federal officers.
On most recent nights, the Portland Police Bureau took an extreme stand-off posture.
When Wolf visited Portland in mid-July, Wheeler said he wasn't invited to meet with the secretary but would not have even if he had been.
Portland Police Chief Chuck Lovell also did not meet with Wolf and, as far as he knew, no one from his department had. The bureau later said that officer Daryl Turner, head of the Portland police union, conferred in person with Wolf.
Trump and administration officials have made clear that violent criminal activity will not be tolerated but that they prefer local and state leaders step forward to police their communities, as opposed to federal forces, Wolf said on Wednesday.
DHS "will continue to re-evaluate our security posture in Portland, and should circumstances on the ground significantly improve due to the influx of state and local law enforcement, we anticipate the ability to change our force posture," he said.