According to Buratha news agency, she arrived in the holy city of Najaf on Monday morning.
She is slated to hold a press conference after her talks with Ayatollah Sistani.
Her visit comes amid protests in Iraq.
More than 200 have been killed and thousands of others wounded since protests erupted in Iraq in early October, with security forces using tear gas and rubber bullets against those taking to the streets.
The Iraqi premier earlier this month lauded the rallies in a statement, saying that the demonstrations, which “shook the political system”, have "achieved much of their objectives" in pushing the Iraqi establishment to "reconsider" its decisions and address the protesters' concerns.
Adel Abdul-Mahdi said that he welcomed continued protests as an expression of “free speech” and change, but urged the protesters to avoid participating in non-permitted street protests and to convene in predesignated areas.