The Arizona sheriff has been a vocal opponent of the Obama administration for years and is known for his tough take on tackling crime and hardline stance on illegal immigration.
Arpaio will appear with Trump in Marshalltown, according to the campaign, a month after appearing at a Trump rally in his home state.
Trump has made ending illegal immigration a focal point of his presidential campaign, and is running neck-and-neck with Ted Cruz in Iowa ahead of ballots being cast Monday.

“I have great respect for Sheriff Arpaio. We must restore law and order and respect the men and women of our police forces. I thank him for his support of my policies and candidacy for President,” Trump said in a statement.

In another statement, Arpaio praised Trump as a "leader" who "produces results and is ready to get tough in order to protect American jobs and families."
"I have fought on the front lines to prevent illegal immigration and I know Donald Trump will stand with me, and countless Americans, to secure our border. I am proud to support him as the best candidate for President of the United States of America," he added.
News of the endorsement was first reported by The New York Times.

The sheriff challenged President Obama's executive actions on immigration, but the Supreme Court recently rejected his appeal to hear his case.
The endorsement comes on the heels of former Alaska Gov. Sarah Palin endorsing Trump last week and Liberty University President Jerry Falwell Jr. endorsing him earlier Tuesday.
—This report was updated at 4:06 p.m.