Trump aide Michael Cohen told The Des Moines Register the real estate mogul will already have announced his plans before the June 10 event. The Iowa caucuses begin the presidential voting.
Last week Trump announced a June visit to New Hampshire, the first primary state.
State GOP Chairman Matt Strawn said he approached Trump last month after seeing him speak to the Conservative Political Action Conference in Washington.
"When he decided to make a CPAC appearance and first started making rumblings of potentially exploring a presidential run, I thought, if that's the case, we need to reach out to him to headline one of our events," Strawn told the Register.
The Lincoln Day banquet is expected to draw a crowd rivaling the more than 1,000 people who turned out to hear former Alaska Gov. Sarah Palin at the party's fall dinner.
Trump told the Register he would campaign aggressively in Iowa if he runs. The June 10 event comes two months before the Ames straw poll that tests candidates' ability to turn out supporters.