The opening ceremony in a tent-shaped stadium will be held at 1440 GMT, ahead of the first match between hosts Qatar and Ecuador.
Few details were available on heads of state attending, but state media said the U.N. secretary general and Algeria's president arrived on Saturday.
The smallest nation to hold soccer's biggest global event, Qatar, a wealthy gas producer, aims to bolster its credentials as a global player, display strength to rivals in the region and placate conservative Sunni Muslim Qataris.
Many of the migrant workers who toiled to prepare Qatar's tournament infrastructure will watch from the sidelines, priced out of the stadiums.
"When we came in it was like a bit of a work site," England fan Neil Gahan said in an area in Doha housing fan portacabins.