Kwesi Appiah scored the winner against non-league side Cray Wanderers at Bromley's Hayes Lane.
The 21-year-old striker slotted home after his penalty was saved by goalkeeper Andy Walker.
Palace's side were mainly made up of youngsters as the first-team were returning from their training camp in Spain.
Kieron Cadogan, who is looking to cement his place in Dougie Freedman's plans after a spell away from the club, had the first opportunity of the game but dragged his shot wide.
Eagles' goal came in the 25th minute when Ibra Sekajja was brought down inside the box, leaving Appiah to net after missing the initial penalty.
Appiah was unlucky not to double his tally as his lobbed effort narrowly cleared the bar before he squandered a golden opportunity to beat the Cray goalkeeper .
The young striker's goal was enough to seal the win for a young Palace side who will be hoping to make an impression on Dougie Freedman's side this season.
Palace XI: Fitzsimmons, Wynter (Akuruka), Daniel, Holland, Taylor (Chambers), Dorman, Fenwick, Sow (Carney), Cadogan, Sekajja, Appiah.
Subs Not Used: Tom King.