Duckett smashed 17 fours and three sixes in his 143-ball masterclass after Australia won the toss and elected to bowl on a batter-friendly wicket in Lahore on Saturday.
Joe Root chipped in with a handy 68 off 78 balls, combining with Duckett for a 158-run partnership.
Their counter-punch helped set the foundations for England to score the highest total in the tournament's history, bettering the 4-347 posted by NZ against the US at The Oval in 2004.
Duckett also set an individual record, with his total the highest ever in Champions Trophy history, betting the 145 from Kiwi Nathan Astle against the US in 2004.
"I thought the way he paced it, the way he played throughout - going through the different gears and managing different bowlers - was excellent," Root said, praising Duckett's innings.
"Just being able to rotate with him, get him on strike and watch him do his thing - he scores in quite awkward areas.Â
"He's difficult to bowl to. He used it all to his strength today and it got us into a really good position."
Carey was picked in the side as a batter only due to the presence of Josh Inglis, but it didn't take long for him to show his value in the outfield.
The 33-year-old stunned the crowd with a diving, one-handed catch at mid-on to dismiss opener Phil Salt for 10 in the second over.
His next catch was a sitter, helping Ben Dwarshuis (3-66) snare his second scalp as England slipped to 2-43.
Duckett and Root settled the ship with a dominant third-wicket stand, and at 2-201 in the 30th over, England were on track for a total nudging 400.
But Root's exit at the hands of Adam Zampa (2-64) slowed down England's charge to a degree.
Duckett carried on, flat batting Spencer Johnson (0-54 off seven overs) down the ground to bring up his ton off 95 balls.
Carey showed his earlier stunner was no fluke, taking another brilliant diving catch to dismiss Harry Brook for three.
Despite wickets falling around him, Duckett surpassed 150, before being trapped plumb LBW by Marnus Labuschagne (2-41) in the search for some late runs.