Despite resolute defending from Barclays Women's Championship side Newcastle United, Palace managed to score two late goals to book their place in the next round.
Larkin was brought onto the field on 73 minutes, as Laura Kaminski looked to the bench to help Palace break down a resilient Newcastle defence.
Just eight minutes later, Larkin found herself with space on the right-flank and her pinpoint cross was met by Ashleigh Weerden, who poked the ball past the goalkeeper to make it 1-0.
As Newcastle pushed for an equaliser in injury time, Palace won the ball high up the field and Annabel Blanchard picked out Larkin on the edge of the box.
The Ireland international lashed a shot at goal, which took a slight deflection and wrong-footed Claudia Moan in the Newcastle net.
