The North Carolina Republican Party voted unanimously on Monday to censure Senator Richard M. Burr for voting to convict former President Donald J. Trump in his second impeachment trial.

The rebuke was the latest fallout for the seven Republicans who sided with Democrats in an unsuccessful effort to find Mr. Trump guilty of inciting an insurrection on Jan. 6, when a mob of Trump supporters rampaged through the Capitol.

The vote by Mr. Burr, 65, who will retire after three terms in the Senate, came as a surprise after he had earlier voted against moving forward with the impeachment trial because of a Republican challenge that the Senate lacked jurisdiction to try a former president.

The North Carolina Republican Party said in a statement on Monday that the decision to censure Mr. Burr had been made by its central committee.

The party “agrees with the strong majority of Republicans in both the U.S. House of Representatives and Senate that the Democrat-led attempt to impeach a former president lies outside the United States Constitution,” the statement said.

Mr. Burr released a brief statement in response saying that it was a “truly sad day” for Republicans in his state.

“My party’s leadership has chosen loyalty to one man over the core principles of the Republican Party and the founders of our great nation,” he said.

Mr. Trump was acquitted on Saturday by a vote of 57 guilty to 43 not guilty that fell short of the two-thirds threshold for conviction. The result was not a surprise because only six Republicans had joined Democrats in clearing the way for the case to be heard by narrowly rejecting a constitutional objection.

Of the seven Republican senators who voted to convict, Mr. Burr is not the only one to face rebuke. The Republican Party of Louisiana, for instance, said after the impeachment vote that it was “profoundly disappointed” by the guilty vote from its home-state senator, Bill Cassidy.

Of the seven, only Mr. Burr and Senator Patrick J. Toomey of Pennsylvania, who is also retiring, will not face voters again. Mr. Toomey was rebuked by several county-level Republican officials in his state in recent days.

Neither senator was particularly vocal in criticizing Mr. Trump while he was in office.

In 2019, Mr. Burr, then the chairman of the Intelligence Committee, subpoenaed testimony from Donald Trump Jr. as part of his work conducting the only bipartisan congressional investigation into Russian election interference. The former president’s son responded by starting a political war against Mr. Burr, putting him and the Intelligence Committee on their heels.

On the day of the vote in the impeachment trial, Mr. Burr laid out his rationale for his guilty vote by saying that the president “bears responsibility” for the events of Jan. 6.

“The evidence is compelling that President Trump is guilty of inciting an insurrection against a coequal branch of government and that the charge rises to the level of high crimes and misdemeanors,” he said. “Therefore, I have voted to convict.”

The chairman of the North Carolina Republican Party, Michael Whatley, released a statement the same day calling Mr. Burr’s vote to convict “contradictory.”

“North Carolina Republicans sent Senator Burr to the United States Senate to uphold the Constitution and his vote today to convict in a trial that he declared unconstitutional is shocking and disappointing,” Mr. Whatley said.

Mr. Burr’s impeachment vote added fuel to speculation that Lara Trump, Mr. Trump’s daughter in-law, will seek the North Carolina Senate seat that Mr. Burr will vacate after the 2022 election. Ms. Trump, who is married to Eric Trump, grew up in the state and has been floating herself as a possible Burr successor for months.

Ms. Trump, 38, is a former personal trainer and television producer who grew up in Wilmington, N.C. A senior Republican official with knowledge of her plans said that while the Jan. 6 riot had soured Ms. Trump’s desire to seek office, she would decide over the next few months whether to run as part of a coordinated Trump family comeback.