In a video statement released Wednesday afternoon, Parker said she struck a deal with the team to "ensure that our Sixers are staying home."
"This is an historic agreement," Parker said in a video posted on the social platform X. "I wholeheartedly believe this is the right deal for the people of Philadelphia."
Parker said the deal for the arena represents $1.3 billion in private investment in the city, hundreds of millions of dollars of tax revenue for the city and the school district, and hundreds of jobs.
"It is the best financial deal ever entered into by a Philadelphia mayor for a local sports arena," Parker said.
She said her administration will be sending legislation to City Council for its consideration.
Council would still have to approve it, Parker noted.
"It's up to us to look at that legislation and see if the proper safeguards are put in place, and if not, add those safeguards in place before an introduction can happen," said Councilmember Mark Squilla, whose district includes the proposed site.
In a statement, the 76ers said, "We are grateful to Mayor Parker and her team for their time and diligence in evaluating our proposal and look forward to advancing to the next steps with City Council."
The team's proposed arena, 76 Place, would be located about a block from Chinatown and has been a hotbed of controversy since it was announced.
Some in the community worry that street parking could disappear, traffic could rise and it could be harder to hold festivals, including in nearby Chinatown.
"To the people of Chinatown, please know that I hear you. We have the best Chinatown in the United States, and I am committed to working together to support it," Parker said.
Chinatown activists who have felt the squeeze of development repeatedly since at least the 1990s had urged the mayor to reject the plan.
They are only now getting some relief from a sunken expressway that cleaved their community in two in 1991, in the form of a $159 million grant to build a park over the six-lane highway and reconnect the area.
Parker, who inherited the 76ers issue when she took office in January, had promised to consider their input. Activists complained Wednesday that she ignored it.
Some of them took to City Hall with homemade lanterns to "shine a light" on the potential consequences. They say the project will increase vehicle traffic in their pedestrian-friendly neighborhood and force vulnerable residents - older people, low-income families and new immigrants - out.
Debbie Wei, of the Save Chinatown Coalition, said the mayor alone should not decide "whether our community should live or die."
"This fight is far from over," she said in a statement. "We are going to fight this, and we are going to the mat. It's on."
But even as voices of dissent persist, so do voices of support. Unions applauded the mayor and leaders of the Pennsylvania Restaurant and Lodging Association also believed this was the right call.
"We see a lot of economic advantages here, not only for our members, but the 80,000 service workers across the region," said Ben Fileccia with the Pennsylvania Restaurant & Lodging Association.
When it comes to the jobs, Dr. Joel Maxcy, Drexel sports business professor, said, "Generally jobs at an arena are service jobs so they're not necessarily high-paying. They're not necessarily full-time, etc., and there could be an offset loss of jobs at Wells Fargo."
Parker's support comes after the state of New Jersey floated a $400 million deal to lure the Sixers to Camden.
"Nothing announced today changes our view that the Sixers should seriously consider New Jersey for their next home. We play until the final buzzer sounds, and we look forward to continuing to make the case for Camden and the Garden State," said NJEDA CEO Tim Sullivan.
Sixers officials have said they want a new arena to be ready by the time the team's lease with its current home, the Wells Fargo Center in South Philadelphia, expires in 2031.
The team now rents the arena from Comcast Spectacor, which also owns the Philadelphia Flyers of the NHL, who also play there. Instead, the Sixers' owners want their own, more modern facility, one they could also rent out for concerts and other events.
Josh Harris, a managing partner of the ownership group, Harris Blitzer Sports & Entertainment, has said the Sixers will build a privately funded facility that "strengthens ties within the local community through investments that prioritize equity, inclusivity and accessibility."
Comcast Spectacor Chairman and CEO Daniel J. Hilferty said they will keep the door open for the 76ers as the plan unfolds while working with the Phillies to expand entertainment venues and jobs at the South Philadelphia complex.
"Either way, we always want what is best for Philadelphia," Hilferty said in a statement.
Team owners say their planned 76 Place would improve a struggling retail corridor near City Hall and capitalize on the city's public transit.
Parker said she would have more to say in a forthcoming presentation.
She said she would also be holding town hall meetings across the city.
The Associated Press contributed to this report.