Football's world governing body FIFA decided to drop Krasnodar and Yaroslavl from the list on Friday, retaining Moscow, St. Petersburg, Kaliningrad, Nizhny Novgorod, Kazan, Samara, Volgograd, Rostov, Sochi, Saransk and Yekaterinburg.
Moscow will have two venues - the 90,000-seat Luzhniki stadium, which will stage the final, and a 45,000-seat arena that is being built by the Spartak club.
"It will be the first World Cup to be held in Eastern Europe and in Russia. I think Russia will have the best World Cup in history," Blatter said earlier, lavishing praise on the hosts.
"I say you already deserve 10 out of 10."
Saransk, smallest of the contenders and with little soccer tradition, was considered an outsider along with Yaroslavl but made the list at the expense of the southern city of Krasnodar.
The venues are grouped into four geographical clusters: central, based around Moscow; northern, involving St Petersburg and Kaliningrad; the Volga region, with Kazan, Nizhny Novgorod, Samara, Saransk and Volgograd; and south, with Sochi and Rostov.
Yekaterinburg, located at the foot of the Ural mountains near the Europe-Asia border, about 1,800 km from Moscow, is in a separate group because of its remoteness from the other venues.