The chiefs of mission in at least 29 countries were informed last week that their tenures would end in January, according to two State Department officials, who spoke on condition of anonymity to discuss internal personnel moves.
All of them had taken up their posts in the Biden administration but had survived an initial purge in the early months of Trump's second term that targeted mainly political appointees.
That changed on Wednesday when they began to receive notices from officials in Washington about their imminent departures.
Ambassadors serve at the pleasure of the president although they typically remain at their posts for three to four years.
Those affected by the shake-up are not losing their foreign service jobs but will be returning to Washington for other assignments should they wish to take them, the officials said.
The State Department declined to comment on specific numbers or ambassadors affected, but defended the changes, calling them "a standard process in any administration."
It noted that an ambassador is "a personal representative of the president and it is the president's right to ensure that he has individuals in these countries who advance the America First agenda".
Africa is the continent most affected by the removals, with ambassadors from 13 countries being removed: Burundi, Cameroon, Cape Verde, Gabon, Ivory Coast, Madagascar, Madagascar, Mauritius, Niger, Nigeria, Rwanda, Senegal, Somalia and Uganda.
Second is Asia-Pacific, with ambassadorial changes coming to six countries: Fiji, Laos, the Marshall Islands, Papua New Guinea, the Philippines and Vietnam affected.
Four countries in Europe - Armenia, Macedonia, Montenegro and Slovakia - are affected; as are two each in the Middle East (Algeria and Egypt); South and Central Asia (Nepal and Sri Lanka); and Latin America (Guatemala and Suriname).
Politico was the first to report on the ambassadorial recalls, which have drawn concern from some lawmakers and the union representing American diplomats.
