Khalil Meek, a longtime spokesman for a coalition of Holy Land Foundation supporters called Hungry for Justice, which includes national Muslim and civil rights groups, said supporters were “devastated” by the verdict.

Image Ghassan Elashi, left, and Shukri Abu-Baker, two of the five leaders of the Holy Land Foundation convicted on Monday. Credit... Left, Irwin Thompson/The Dallas Morning News, via Associated Press; Right, Jessica Rinaldi/Reuters

“We respect the jury’s decision, but we disagree and we think the defendants are completely innocent,” Mr. Meek said. “For the last two years we’ve watched this trial unfold, and we have yet to see any evidence of a criminal act introduced to a jury. This jury found that humanitarian aid is a crime.”

He added, “We intend to appeal the verdict, and we remain convinced that we will win.”

The prosecutor, Barry Jonas, told jurors in closing arguments last week that they should not be deceived by the foundation’s cover of humanitarian work, describing the charities it financed as terrorist recruitment centers that were part of a “womb to the tomb” cycle.

After the mistrial last year, critics said the government had offered a weak, complicated case and had failed to recognize that juries were not as quick to convict Muslim defendants accused of supporting terrorism as they had once been. Prosecutors spent more time in the second trial explaining the complexities of the case and painting a clearer picture of the money trail. They also dropped many of the original charges.

“Today’s verdicts are important milestones in America’s efforts against financiers of terrorism,” Patrick Rowan, assistant attorney general for national security, said in a statement. Mr. Rowan added that the prosecution “demonstrates our resolve to ensure that humanitarian relief efforts are not used as a mechanism to disguise and enable support for terrorist groups.”

Nancy Hollander, a lawyer from Albuquerque who represented Mr. Abu-Baker, said the defendants would appeal based on a number of issues, including the anonymous testimony of an expert, which she said was a first.

“Our clients were not even allowed to review their own statements because they were classified  statements that they made over the course of many years that the government wiretapped,” Ms. Hollander said. “They were not allowed to go back and review them. There were statements from alleged co-conspirators that included handwritten notes. Nobody knew who wrote them; nobody knew when they were written. There are a plethora of issues.”