Janmaat - an off-season recruit from Eredivisie side Feyenoord - made his Newcastle bow on Tuesday, playing 55 minutes in the club's 2-2 pre-season draw with Huddersfield Town.
Despite the match at John Smith's Stadium being Janmaat's first since the Netherlands' third-place play-off at the World Cup last month, Pardew said the Dutchman will be ready for the visit of the champions on August 17.
"He is a class act. He will play for us against Man City there is no doubt about that," said Pardew, whose side tackle Real Sociedad in their final friendly fixture on August 10.
"He is fit and injury free. He's had 60 minutes tonight and hopefully he will get 80 on Sunday."
Newcastle have been active in the transfer market as the 2014-15 campaign edges closer, with Ayoze Perez, Jack Colback, Siem de Jong, Remy Cabella and Emmanuel Riviere all arriving at St James' Park in the close-season.
The Premier League team have also swooped to sign Nottingham Forest pair Jamaal Lascelles and Karl Darlow, though the double deal is yet to be officially confirmed.
Defender Lascelles, 20, and goalkeeper Darlow, 23, are expected to be loaned back to Forest for the Championship season.
However, Pardew still expressed his delight with duo's imminent arrival.
"Every time we sign a player we think it's good business," he said.
"We think it's part of what we do.
"It's our judgement. They are two great assets for Newcastle United."
