Ms. Smale, a British citizen, is currently The Times’ bureau chief in Berlin. She had been the executive editor of The International Herald Tribune, based in Paris, for four years, before it was renamed The International New York Times in 2013. She was the first woman to head that newspaper.

Image Alison Smale Credit... Nadine Rupp/Getty Images

After joining The Times in 1998, Ms. Smale became deputy foreign editor in 2002. Before that, she had reported extensively across Europe for The Associated Press, covering the fall of the Berlin Wall in 1989 and war in the Balkans in the 1990s. She was posted in Moscow from 1983 to 1987 and is fluent in Russian.

Ms. Smale’s appointment to the United Nations is unusual partly because she comes directly out of journalism. Her recent predecessors had come mainly from government service, including Cristina Gallach of Spain, who was under secretary general for communications and public information until mid-April.

One of Ms. Smale’s major challenges will be to explain to the world why the United Nations matters, at a time when its effectiveness, and even its relevance, are under increased scrutiny.

The organization also faces acute pressure from its biggest funder: the United States, which under President Donald J. Trump, has threatened to cut funding. Washington pays 22 percent of the United Nations’ core budget and 28 percent of its peacekeeping budget.