The 24-year-old tight-head has been behind British & Irish Lion Adam Jones in the pecking order at both club and country in recent years.
Jones has been sidelined with a an elbow injury but returned to action in the 37-6 victory over Glasgow last weekend.
There had been calls for Jones to be called straight back into international action.
But Gatland rebuked those suggestions and shown faith in the Ospreys Test rookie by selecting him for his fourth consecutive clash.
"It's a vote of confidence in Craig Mitchell, he's not had enough credit for how well he has played," said Gatland.
"His scrummaging has been good and his tackling, and work around the field, has been outstanding.
"Craig has shown what he can do when he's been given a consistent run of games.
"We all know what Adam can do, and the qualities he has, but it's the World Cup we are thinking of and increasing our depth at tight-head with Craig."
Mitchell was earmarked as a tight-head with potential from a young age and made his Magners League debut during the 2005-6 season. He has had to bide his time behind Jones but has gone on to make 23 further league appearances.
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