Colin Myler, the editor in chief of The New York Daily News, is stepping down after less than four years on the job, according to a memo sent to staff members on Friday.

Mr. Myler “will be leaving the News to return to London,” the paper’s owner, Mortimer B. Zuckerman, and its chief executive, Bill Holiber, said in the memo. “The sole reason is one that you might be well aware, Colin and his wife, Carol, are yearning to be reunited with their family and four grandchildren.”

Mr. Myler’s deputy, Jim Rich, who has held a variety of roles under Mr. Myler, including overseeing the paper’s website, will take over. Mr. Myler will stay on until the end of the year before handing off to Mr. Rich, who once worked at the News’s archrival, The New York Post.

A seasoned British tabloid editor, Mr. Myler, 63, joined the newspaper in early 2012. It was a difficult time for New York’s tabloid newspapers, which battled dwindling circulation and competition from fast, free websites on the kinds of stories the papers specialize in — gossip and sports, among others.

He has focused on expanding the newspaper’s web presence, while battling to retain the relevance of its front page. His supporters pointed out recent scoops, including news of the New York Police Department’s mistaken arrest of the former tennis star James Blake this week.

At the same time, his tenure was marked by alarming and precipitous declines in the popularity and stability of the News, once a titan with millions of readers, because of challenges facing the industry. By the time of his departure, the paper was losing $20 million to $30 million a year, according to a person familiar with its business operations, who spoke on condition of anonymity to describe confidential information, and its circulation had been battered, hit especially hard by a decline in newsstand sales, which were once the lifeblood of its operations.

Mr. Zuckerman, apparently weary of the losses, put the newspaper up for sale this year. But after a grueling process, which many described as deeply unsettling for the newspaper’s staff, he decided that none of the offers he had received were enticing enough, and last month he said the paper was no longer for sale.

Mr. Myler had been set to leave, after consultation with any new owner, after the sale. His departure, said one staffer, who described the internal dynamics on condition of anonymity, is the latest in a series of events, including the sale process, which had cast the newsroom into doubt and instability. In a note to the staff, Mr. Myler said that the decision had been “incredibly hard.”

When Mr. Myler arrived at The Daily News, had left a scandal behind in Britain. He was the editor of the News of the World tabloid, which was shut in 2011 after accusations that it had, under previous editors, illegally intercepted the voice mail messages of newsworthy figures, seeking scoops.

He was called to testify before Parliament and saw former colleagues on trial, even jailed. He moved to New York months later, and he will be returning just as those legal actions draw to a close.

Another major figure in the scandal, Rebekah Brooks, a former editor of The News of the World who stood trial, was recently reappointed to her old job as the head of Rupert Murdoch’s British news media properties.

Though Mr. Myler is not retiring, it is unclear what his next role might be.