The stoning takes place at the scene where Islam says that Satan tempted the biblical patriarch Abraham.
Iraqi pilgrim Bashar Shaker Mahmud spoke of the elation that he felt taking part in the ritual.
"There are no words to describe this situation," he said. "May God bless all Muslims and make their pilgrimage a success."
The stoning of the pillars is among the most followed, and most dangerous, elements of the annual pilgrimage.
This year's stoning ritual tests new safety measures in place to avoid a tragedy similar to the scene in the last hajj, when 362 pilgrims were crushed to death.
Official figures suggest that nearly 2.4 million Muslims from 187 countries are participating in Islam's annual hajj, more than 40 percent of them women.
Eid Al-Adha Begins
As the hajj wound down, Muslims around the world are celebrating the festival of Eid al-Adha, to mark Prophet Ibrahim's willingness to sacrifice his son Ismael for Allah.
The three- or four-day Eid al-Adha is among the most sacred of Muslim holidays, and begins the day after hajj pilgrims descend from Mount Arafat, east of Mecca.
During the Eid al-Adha festival, Muslims sacrifice animals and distribute the meat among family, friends, and the poor.