Ahmadinejad was invited by President Jalal Talabani, but will be hosted by Vice President Khudayr al-Khuzaie, as Talabani is abroad for medical treatment, Ali Mussawi said.
The outgoing Iranian president, who arrives on Thursday, will also meet Maliki, Mussawi said.
Ahmadinejad, whose term ends early next month, will visit the shrine of Imam Hussein in Karbala and that of Imam Ali in Najaf, two of the holiest sites in Shiite Islam, Mussawi said.
Iraq and Iran fought a bloody 1980-88 war launched by now-executed dictator Saddam Hussein, but have drawn closer since his overthrow by US-led forces in 2003, which ultimately paved the way for expanded Iranian influence in Iraq.
