Stoke, unbeaten in their last nine matches were on the sharp end of a ruthless Palace performance as the Eagles romped to their biggest win of the season.
The match started at a cracking pace with three goals inside the first seven minutes.
Johnson put the home side on their way after five minutes, controlling Mark Hudson's inch-perfect pass to drill home from ten yards.
John Eustace levelled immediately from a free-kick which he struck low from 25 yards out.
The excitement continued as Palace launched an attack at the other end and were awarded a penalty when Paul Williams dragged down Julian Gray. Johnson made no mistake with his trusty right foot, with a firmly struck spot-kick past Ed de Goey.
Williams conceded a second penalty when he brought down Johnson and the Palace hit man picked himself up and completed his hat-trick, with another perfect penalty.
Tony Pulis' outfit thought they were back in it through Clive Clarke's 30-yard shot on 44 minutes, but straight from the restart Michael Hughes made a solo run through the heart of the Stoke defence for a superb solo goal to give Palace a 4-2 half-time lead.
Neil Shipperley headed a fifth from a Wayne Routledge cross before Stoke showed they were not giving up that easily, as Carl Asaba converted a third penalty of the match after Tony Popovic brought Kris Commons.
That came after 82 minutes but there was enough time for Routledge to hit a brilliant sixth goal for Palace to round off a magnificent performance - leaving Dowie to be cheered off by the Palace fans after the final whistle.