He'd once called her a superstar manager, but very few New Yorkers approved of her.
"We both agreed the story had become about her and not about the students and this is the right thing to do," Bloomberg said.
So the mayor turned to one of the first people who joined his administration 10 years ago - a likeable, former teacher Dennis Walcott, who has been his Deputy Mayor for Education. (Click here to read Walcott's bio)
"I consider myself very blessed and very lucky to be asked. To me, I'm just a guy from Queens whose parents were raised in Harlem," Walcott said.
But the news was part and parcel of what we've seen a lot out of city hall lately. The mayor's third term began a year ago, and it's been a barrage of bad news.
The big Christmas snow blizzard that paralyzed the city.
A fiscal crisis that will likely lead to 6-thousand fewer teachers and 20 fire companies closed.
And now Black has come and gone.
Bloomberg said he takes full responsibility for Black not working out as schools chancellor. The two met Thursday morning and decided it was best for her to step down.
"The progress we have made in our schools over the last nine years has been extraordinary," said Mayor Bloomberg. "Cathie Black became Chancellor of our school system earlier this year and worked tirelessly to continue to build on our progress. I have nothing but respect and admiration for her, but we both agree it is in the City's best interest if she steps down as Chancellor. I am pleased to announce that Dennis Walcott a key part of, and a leader on, all of our education reform initiatives will serve as the City's new Schools Chancellor."
Black, the former Hearst chairwoman and former publisher of USA Today, has been largely shielded from the public since Bloomberg announced her appointment.
Black did not attend the mayor's news conference, but later speaking outside her home, Black said that she bore no ill will.
"It's been a great privilege to serve the city of New York and the mayor for three months," she said. "I have loved the principals and the teachers and the kids. Dennis Walcott is a great guy. We have a wonderful relationship and I wish everybody the best."
Insiders have called the whole Black fiasco, part of what Bloomberg was warned about, the third term blues.
"It is a battle scar. He has had many over the years, this one particularly, because education is so important an issue. And he put so much political capital in to Chancellor Black that it is a scar. It will affect his legacy," Lee Miringoff of Marist said.
And now Bloomberg's opponents are using today's development as fodder in their fight to change who's running our schools.
"We need to end mayoral control. This is a clear indication he has poor judgment and should not be running our schools," Councilman Charles Barron said.
"If we had municipal control the mayor would have the city council would have said no, but because we have no check we got to this point," Councilman Jumanne Williams said.
Critics said that Black's lack of experience in public education and the secrecy surrounding her appointment put her at a disadvantage when she took the reins of the 1.1 million-pupil school system.
INTERACTION: TELL US YOUR THOUGHTS
Earlier this week a NY1/Marist poll found that 17 percent of New York City adults say the former media executive was doing a good or excellent job, down from 21 percent in early February. Twenty-three percent say they don't know how to rate her work or haven't ever heard of her.
When faced by heckling from hostile parents she heckled them back. And she made a misstep by joking that school overcrowding could be fixed with birth control. ---
Statements on new appointment
Former chancellor Joel Klein
Dennis was my partner during the eight years I served as Chancellor. He is a superb selection. He knows the field of education, the DOE, the issues, the people, and the politics. Most of all, he's a fighter for kids.
Queens Borough President Helen Marshall:
Dennis Walcott has the experience, expertise and talent to take over the helm as Chancellor of the nation's largest school system. As a former teacher, and deputy mayor for almost a decade, Dennis is fully aware of the high stakes involved in each child's education and, as the parent of children who went to public schools, knows full well what goes on in the city's classrooms. As "a guy from Queens," and in his role as deputy mayor, he has visited hundreds of schools over the years and been involved in every issue related to education during his years in the Bloomberg Administration. He has a steady hand and a clear understanding of the vital role that parents play in their children's education. He works well with them and has always been responsive to their concerns during his many visits to the Parents Advisory Board here at Borough Hall. On behalf of the students and parents here in Queens, I wish him good luck on his new assignment and look forward to working with him on behalf of the children of Queens.
Brooklyn Borough President Marty Markowitz Statement
"I join all of Brooklyn and our borough's 300,000 public school students and their families in wholeheartedly welcoming Dennis Walcott?a proud son of New York City and product of the public school system, educator and, perhaps most importantly, parent and grandparent?as New York City Schools Chancellor. Deputy Mayor Walcott has been actively involved in the city's education community, and was instrumental in enacting many of the recent positive reforms. His expertise will help stabilize the system and move it forward. I spoke with Deputy Mayor Walcott this morning and pledged to support him in every way possible, and we are excited to work together as we help our children reach the zenith of their potential."
Statement from James Merriman of the NYC Charter Schools Center on the appointment of Dennis Walcott as NYC Schools Chancellor
"Dennis Walcott has been instrumental in the city's efforts to expand the number of high-quality public schools options, including public charter schools, that New York families have access to, and his appointment will bolster the city's ongoing efforts to drive comprehensive education reform. He's the right choice for our school children, and we look forward to working with him."
Statement by Asemblyman Hakeem Jeffries
"For less than 100 days, our 1.1 million public school children have been on a rudderless ship in the education high seas, and parents were left without a qualified captain.
"The resignation of Cathie Black represents and extraordinary public acknowledgement by City Hall that her appointment did not serve the best interest of our public school children. This administration has had several public policy successes but has often been reluctant to admit failures. Many parents and community stakeholders remain skeptical about the Department of Education and its policies. The departure of Cathie Black creates an opportunity for the DOE to move in a different direction. I have disagreed often with Mayor Bloomberg on his education decisions, but the appointment of Dennis Walcott is a significant step in the right direction."