Gonzalez represents northeast Ohio's 16th Congressional District, in the northeastern part of the state.
The Ohio Republican Party censured Gonzalez in May for voting in February to impeach Trump. Gonzalez has stood by his impeachment vote in the face of fierce pushback from his party's conservative wing.
It remains unclear whether any of the other House Republicans who joined Gonzalez in voting for impeachment will follow in his footsteps.
In an interview with The New York Times announcing his decision, Gonzalez called Trump “a cancer for the country” who represents a threat to democracy and said that Jan. 6 had been “a line-in-the-sand moment” for him.
While he said there seemed to have been a moment then when the party might break with the former president, he has been dismayed by its decision to instead embrace Trump.
“This is the direction that we’re going to go in for the next two years and potentially four, and it’s going to make Trump the center of fund-raising efforts and political outreach,” Gonzalez told the newspaper. “That’s not something I’m going to be part of.”
He said he plans to spend his time now working to prevent Trump from being elected to the White House again.
“Most of my political energy will be spent working on that exact goal,” he said.
Trump called Gonzalez's decision not to seek reelection “no loss for Ohio or our Country.” In a statement Friday that also praised Miller, the former president said Gonzalez quit after losing popularity following his vote for impeachment.