Updated at 9:47 p.m.
McCarthy's speech is expected to focus on the House GOP's "Better Way" agenda and on building party unity.
The California Republican was first elected to the House in 2006. McCarthy shocked the political world last year when he dropped out of the race to succeed John A. Boehner of Ohio as speaker of the House.
In addition to McCarthy, Sens. Joni Ernst (R-Iowa) and Ted Cruz (R-Tex.) are slated to speak at the convention. House Speaker Paul D. Ryan (R-Wis.) is also reportedly speaking at the gathering where Donald Trump is expected to be officially nominated for president.
A Trump campaign spokesman did not immediately respond to a request for comment. A McCarthy spokesman did not immediately comment.
Trump has not yet released his full slate of convention speakers. The convention kicks off on Monday.