Kimi Yoshino, who has led The Baltimore Banner for three and a half years as its first editor-in-chief, building it from a concept written on a sheet of paper into a Pulitzer Prize-winning news organization with a growing subscriber base, told her staff Thursday that she will leave her job to become a senior editor at The Washington Post.

“She has been our architect — the person who took an audacious idea and with grace and grit made it real,” said Stewart Bainum Jr., The Banner’s founder and chair of its board. “We had a vision. We had no playbook. We just had a belief that local journalism still matters, and she made it happen.”

The Banner, one of the largest nonprofit news organizations in the country, will immediately launch a national search for a new editor-in-chief by hiring a recruitment firm and forming an internal committee, Chief Executive Bob Cohn said.

“We are going to find the right editorial leader to continue and honor the work that Kimi has done,” Cohn said.

Brian McGrory, a Banner board member, the former editor-in-chief of The Boston Globe, and the current chair of the Journalism Department at Boston University, will help lead the newsroom on an interim basis, Cohn said, and will have final say on all editorial matters.

Yoshino said the job at The Post, where she will become a managing editor with a broad portfolio overseeing features, sports, local news, investigations and data, was an opportunity to make a difference at a fabled organization facing significant difficulties.

“Just as I was driven by the challenge to move to Baltimore to help save local news, I’m now excited to tackle another important mission,” Yoshino said. “I am eager to help reinvigorate one of the most storied institutions in American journalism.”

Last year, The Post reportedly lost roughly 250,000 subscribers after the organization’s owner, Jeff Bezos, blocked its opinion section from endorsing a presidential candidate and later ordered its opinion pages to embark on a narrower direction focused on free markets and personal liberties. Many prominent Post journalists departed in protest.

When Bainum, a Maryland native and the chair of Choice Hotels International, decided to launch The Banner in the summer of 2021, he pledged $50 million of support over five years. After a monthslong search for its top editor, he chose Yoshino, then the managing editor of the Los Angeles Times.

During her 21 years at the newspaper, she helped guide a series of stories that uncovered widespread public corruption in Bell, California, coverage that won a Pulitzer Prize for public service, considered journalism’s top prize. She also pushed digital transformation and led the reinvention of several departments, including business and features.

In their first meeting, held over Zoom during the pandemic, Yoshino “wasn’t trying to please me,” Bainum recalled. “She said exactly what she thought,” a trait that he said impressed him.

In fact, Yoshino, who had never lived outside California, was intrigued. “It was a once-in-a-lifetime opportunity to build a local news organization and try to prove that local news can be sustainable,” she said Wednesday. After hours of interviews and two days in Baltimore, she agreed to take the job.

When she arrived in Baltimore in January 2022, she had just hired three reporters to set up shop in a makeshift space in the Inner Harbor.

When one asked where the reporters’ notebooks were, her first thought was, “Wow, we really are a startup.” No one on the freshly hired business side of the operation had known to buy reporters’ notebooks, or even knew what they were.

Yoshino was free to decide what the nonprofit news startup should become and how it would be different, and less constrained, than the print-focused legacy news outlets that were suffering across the nation.

As much of the news industry remained under duress, especially at the local and regional levels, Yoshino went on a hiring spree, adding 35 reporters and editors by the time The Banner launched its website on June 14, 2022.

The Banner has continued to add staff, growing to 85 journalists and 45 business-side employees. It has expanded its ambitions into the realms of business, sports and breaking news and expanded its geographical footprint from Baltimore to surrounding counties with plans to expand across the state.

The Banner has 64,000 subscribers and is projected to become financially sustainable by 2027.

This month, The Banner won the Pulitzer Prize for local news for a 2024 series, in partnership with The New York Times, on the rampant opioid overdose crisis in Baltimore and the government’s failure to monitor and address it.

Yoshino is known within the organization for fostering a culture of collaboration. She was once asked by a member of the leadership team if she hired staff based on “niceness.” Her wry answer: “Sort of.”

“I have tried really hard to build a strong culture at The Banner — to do it right, to uphold values and develop a strong sense of mission,” Yoshino said.

Lynn Venetoulis, widow of Ted Venetoulis, who helped found The Banner, said her husband was “smiling down from heaven the day Kimi Yoshino was hired....Kimi and her talented staff have turned The Banner into an enterprise that is no longer an experiment but a thriving Pulitzer Prize winning-enterprise that is here to stay.”

She became an enthusiastic resident of Baltimore, buying a house with her husband, and a vocal public champion of The Banner.

She spoke on behalf of the fledgling news organization at dozens of community events, appealing to potential subscribers and financial supporters. Inside the newsroom, Yoshino gained a reputation for pushing reporters to hold the powerful accountable.

“She’s got a nose for news. She’s relentless in pursuing the story and fearless about publishing,” said Cohn, who became The Banner’s CEO in early 2024.

While Yoshino has deep respect for traditional journalistic values, Cohn also praised her “entrepreneurial spirit, which is essential in today’s media environment.”

She is “unafraid about inventing the future.”

Besides the Pulitzer, The Banner won a slew of national awards under Yoshino’s leadership — including for the Key Bridge disaster and a series about a Baltimore-based church that hid alleged sexual impropriety by some of its leaders.

It also published an investigation that revealed allegations of inappropriate sexual behavior by Justin Tucker, the most accurate kicker in NFL history, at spas and wellness centers around Baltimore; Tucker was released by the Ravens this month.

Banner journalists also revealed earlier this year that thousands of Baltimore students are unable to reliably get to school using mass transit.

At the same time that she pushed investigative work, Yoshino has encouraged reporters to think of lighter stories and interesting ways to tell them, hoping to entice readers with a sense of surprise each day.

Washington Post Editor Executive Editor Matt Murray said Yoshino will oversee areas that have been strengths of The Post historically, but “where we also think we can have an injection of new life, new opportunities.”

“I think she’s going to bring a refreshing, creative, exciting approach to thinking about areas like features and sports,“ he said. ”Thanks to The Banner, particularly, she understands the digitally evolving entrepreneurial state of the business.”

Bainum said he values openness, collaboration, integrity and ambition — and will look for those in the next leader.

“She is a uniquely empathetic leader, who deeply respects her room, just like the room deeply respects her,” said McGrory, who also filled in at the Banner in 2023 during a transition between CEOs. “Kimi has been more than a great editor for The Banner, she’s an embodiment of what The Banner strives to be.”