The 25-year-old former Charlton midfielder bulleted a 25-yard beauty through the stretching hands of in-form keeper Andy Lonergan.
Palace's response came only two minutes after Preston star man Ross Wallace had started the scoring with a dreamy free-kick.
Scotland ace Wallace, formerly with Sunderland, waited forever to take the free-kick awarded for a yellow-card challenge by defender Jose Fonte on striker Chris Brown.
The wall procedures were finally completed and Wallace coolly bent his shot from outside the penalty box beyond the flailing arm of Argentine keeper Julian Speroni.
Eagles boss Neil Warnock said: "Darren's goal was fantastic. He improves every week and plays with a smile on his face. He can shoot from anywhere and rarely gives the ball away."
Wallace, whose side have only three wins at Deepdale this season, said: "It was disappointing that Palace's equaliser came so quickly after our goal.
"But we have to keep fighting for the three points - they won't just come to us."
Wallace's opener arrived in the 35th minute and was followed almost immediately by Ambrose's leveller from the edge of the box.
And, just before the break, a 25-yard free-kick by Ambrose flew past Lonergan's post.
Early in the second half Ambrose measured up a 30-yard drive which Lonergan pushed away.
Preston's best chance to break the deadlock came in the 83rd minute when Wallace set up Richard Chaplow, who fired wide.
Preston boss Alan Irvine said: "I was surprised that Chappy missed the target. It was our best move."
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