A man who stabbed the author Salman Rushdie more than a dozen times was found guilty on Wednesday of aiding a foreign terrorist group and carrying out the orders of the Iranian government, which had called for Mr. Rushdie’s death more than three decades ago.

Hadi Matar, a young man who had been enraged by Mr. Rushdie’s work, rushed onstage at a retreat in western New York in August 2022 and stabbed him repeatedly. Mr. Rushdie survived the attack, but was left with severe nerve damage and blind in his right eye.

Mr. Matar was convicted of attempted murder in state court last year and sentenced to 25 years in prison. On Wednesday, Mr. Matar, 28, was convicted of providing material support to a terrorist group and committing an act of terrorism that transcended national boundaries.

The verdict, which was reached by a federal jury in Buffalo after just two hours of deliberation, means Mr. Matar could spend the rest of his life in prison. He is set to be sentenced in November.

Mr. Matar showed no response in the marble-and-wood courtroom as the verdict was read aloud. He kept his head lowered, his chair swaying slowly from side to side.

Nathaniel L. Barone II, a lawyer for Mr. Matar, said afterward that he was disappointed with the verdict, which he said he would appeal. The current war with Iran, he said, presented an inherent challenge in convincing jurors of Mr. Matar’s innocence.