The Republican presidential nominee is due to campaign on Wednesday evening in Jackson, Mississippi, as Mr Farage visits the southern US state.
Mr Farage is expected to talk about how the “anti-establishment beat the establishment” to bring about Brexit.
Raheem Kassam, a former UKIP adviser, told the Press Association that Mr Farage will not endorse the Republican candidate.
“As I understand it,” Mr Kassam said, “I think the plan is for him to speak ahead of Trump’s speech, and basically just to walk the audience through the Brexit campaign and how the anti-establishment beat the establishment.”
Ahead of the appearance, Mr Farage appeared on the radio show SuperTalk Mississippi.