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The tournament, won for a fourth time by Germany, featured a record-equalling 171 goals, some shock results and was described by some as the best ever.
Blatter says Brazil outshone South Africa, which was awarded a mark of 9 after it staged the event in 2010.
There were fears surrounding security, transport and stadiums, but these proved largely unfounded.
Most of the drama of the 20th World Cup came on the pitch.
A 5-1 thrashing of holders Spain by the Netherlands set the tone, with underdogs Costa Rica, Algeria and Colombia all impressing in the knockout stages.
The eventual champions humbled hosts Brazil 7-1 in the semi-finals, before a 1-0 extra-time victory over Argentina saw them take the title.
There was controversy, too, with Uruguay striker Luis Suarez handed a four-month ban for biting Italy defender Giorgio Chiellini
"As a footballer, such a punishment hurts," said Blatter at his final news conference in Rio. "But as Fifa president, I have to accept the decisions that are taken by our independent committees."
Blatter was booed at several grounds during the World Cup but said he had "to live with that".
However, he reacted angrily when one female reporter put it to him that Fifa, football's world governing body, is corrupt.
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"Listen lady," he said. "When you speak about corruption, then you have to present evidence."
Fifa general secretary Jerome Valcke described the World Cup in Brazil as "truly unique" and called on the hosts of future tournaments to take inspiration.
Russia will host the competition in 2018, while Qatar is scheduled to stage the tournament in 2022.
"The people from Russia and Qatar who have been in Brazil, they have learned a lot and they know what the challenge is," Valcke told the BBC.
"I'm sure the next two World Cups will be as beautiful as this one... different, but as beautiful as the one here in Brazil."
He added: "When you take the responsibility to organise a World Cup, you have to understand that you have to be the best and you have to deliver the most important event."
Fifa president Sepp Blatter has awarded the 2014 World Cup in Brazil a mark of 9.25 out of 10.