Kathryn is set to turn 23 on March 26.
Alden led the staff and crew in singing the "Happy Birthday" song as he carried the birthday cake for Kathryn.
According to the film's director, Cathy Garcia-Molina, the birthday surprise came early because, "baka hindi ka na namin makita, e!"
Kathryn is set to take a birthday vacation together with family and friends at an undisclosed beach venue.
After blowing her birthday candle, Direk Cathy teased the Kapamilya actress for taking too long to think about her wish.
The young actress said, "Para sa atin lahat ito!"
The two are set to play OFWs in the movie to be shot in Hong Kong.