Daniel Arrigg Koh has the lineage and resume of a luminary on the rise. The chief of staff to Mayor Martin J. Walsh holds two degrees from Harvard and hails from a family that includes a diplomat, influential medical doctors, legal scholars, and advisers to the powerful.
Koh interned for the late senator Edward M. Kennedy and advised former mayor Thomas M. Menino. He can sing, play guitar, and act on stage. He can field a baseball and has run 13 marathons. For a charity fund-raiser in his last job, Koh was Mr. August in a men’s pin-up calendar, nibbling seductively on the earpiece of pair of eyeglasses.
Oh, and he’s 29 years old.
Walsh liked Koh’s resume. He liked his ideas. But what really struck him about Koh was his humility.
“He said, ‘I’m going to make some mistakes as long as you can live with that,’ ” Walsh recalled in an interview Friday, which was Koh’s first full day at City Hall. “I like somebody being humble like that, admitting they are not always going to be right.”
The inner circle of Walsh’s budding administration is stocked with political warhorses and longtime confidants. That’s another way in which Koh stands out. He has known Walsh for just a month, but as chief of staff he will oversee men and women who forged lifelong bonds in the hard-fought campaign that brought Walsh to power. Walsh has made it clear that Koh’s status as a newcomer will not impinge on his authority to lead.
“He has said to me, ‘You’re the guy. You’re in charge,’ ” Koh said in an interview. “He has empowered me to make decisions and be the guy to run the office and help him run the city.”
In the last month, Koh said he has been embraced by Walsh’s team. Top campaign adviser Joseph Rull phoned Koh moments after the appointment was announced, Koh said. The next call came from another close aide, Joyce Linehan.
Rull and Linehan have joined Koh in the mayor’s office along with another longtime Walsh pal, state Representative Eugene L. O’Flaherty. Speculation already abounds in City Hall about who will wield power in the administration.
“I don’t worry about it because I know,” said Koh, who will be paid $152,000 annually. “And I’m not territorial in that way.”
Koh is slender with jet black hair and a full smile. His booming voice complements his gregarious, quick-with-a-handshake personality. He dresses with a touch of style but wears a simple watch with a white face and a single red star. The watch, a gift from his uncle, a South Korean general, has four characters from the Korean Hanja script that convey the family motto: Talent must not come before character.
Koh was born on New Year’s Day 1985 at Brigham and Women’s Hospital. His mother, Dr. Claudia A. Arrigg, is an eye doctor with a practice in Lawrence whose grandparents emigrated from Lebanon. Koh introduces himself with three names — Daniel Arrigg Koh — to honor his mother.
His paternal grandfather was South Korea’s ambassador to the United States. His father, Dr. Howard K. Koh, is the former state public health commissioner and now serves as assistant secretary for health in the Obama administration. His uncle, Harold Koh, served as dean of Yale Law School and was legal adviser to Hillary Clinton when she was secretary of state.
Daniel Arrigg Koh grew up in Andover, the middle of three children, all of whom went to Harvard.
Koh seemed determined to savor every moment of college, according to a roommate, John Voith. Koh played second base on the junior varsity baseball team, dabbled in theater, and sang in the glee club. He had a freshman seminar with controversial former Harvard president Lawrence H. Summers, who sent Koh a note when he was appointed chief of staff. “Best professor I ever had,” Koh said.
Voith described his former roommate as a genuine, fiercely loyal friend. Koh treasured his mixed heritage, Voith said, and it made him adept at understanding different backgrounds and perspectives. But more than anything, Koh is passionate, his friend said.
“When he gets engaged, he’s all in,” Voith said. “He’s going to blow away any expectations. . . . And he’s in love with Boston.”
In the Harvard Crimson in 2005, Koh described his ideal date as, “a cool girl at Fenway Park during Game 7.” While living in New York after college, he tweeted photographs of fall foliage in Boston’s Public Garden and blasted a link to an article with the headline “11 reasons why Boston is so much better than NYC.”
Koh worked most recently at Huffington Post, a news website where he served as chief of staff to media maven Arianna Huffington. His job evolved from Huffington’s personal chief of staff to helping her oversee the entire organization of 700 to 800 people. In his last post with the company, Koh was general manager of HuffPost Live, the website’s streaming video network.
The transition from the Globe-trotting Huffington to Boston’s new everyman mayor may not be as dramatic as it appears.
“I’ve actually found them to be quite similar,” Koh said. “Arianna never saw HuffPost as some huge profit-making machine for her. It was always, ‘How do we change the world and help people doing it?’ Mayor Walsh is very similar. When we first sat down, he said the first thing I want to do is help people.”
Koh’s path to City Hall began with Menino’s last chief of staff, Mitchell B. Weiss, who floated Koh’s name. Both men went to Harvard College, Harvard Business School, and followed a well-worn path from Cambridge to the mayor’s office as part of a fellowship program. When Koh applied for the fellowship, Weiss interviewed him. Koh showed a PowerPoint about how to restructure Menino’s social media presence.
Walsh had never met Koh, but he felt a kinship with his father. As a novice state representative 15 years ago, Walsh worked on substance abuse treatment and prevention with Dr. Koh when he was public health commissioner. Walsh spoke openly about his own struggle with alcoholism, and it made an indelible impression on Dr. Koh, although the two men have not spoken in a decade.
At Weiss’s suggestion, the younger Koh sent Walsh an e-mail after the November election. They spoke on the phone. Koh came to interview in Boston. He brought Walsh a list of ideas and wrote a job description outlining his vision for a chief of staff.
“After about five minutes, I just knew,” Walsh said. “We just clicked.”
Koh felt the same connection. “I knew I wanted to work for him,” he said.
“We grew up very differently, Dan and myself,” Walsh said. “But I feel a sense of him having street smarts, which is very important in city government.”
A note of caution about the job came from Koh’s uncle and father, who worried about the rough and tumble world of politics.
“These jobs are never easy. There are always infinite needs and finite resources,” Dr. Howard K. Koh said in a phone interview from Washington. “But there’s also a tremendous opportunity to make a difference. I know Dan was passionate about going into public service. So when this opportunity arose even though I’m a protective dad, I was also a very, very proud parent.”
His son understood.
“That was just a dad being a good dad,” Koh said. “I assured him I was ready for it. My skin is thick enough.”
Koh has given up his New York apartment and signed a lease in Boston’s West End, near City Hall. His sparsely decorated office includes a framed photograph of him with his new boss.
Walsh signed the picture and added a message: “You better be good.”Andrew Ryan can be reached at email@example.com Follow him on Twitter @globeandrewryan.