Old Lady Princess is meant to marry Ice King in the episode "When Wedding Bells Thaw." When Ice King tells Finn and Jake that he is getting married, she is seen riding in a wagon with a bunch of female penguins, who take her to her bachelorette party. She is cursed by an engagement ring given to her by the Ice King. The ring is spiky, magical, and made of ice, and it tricks her into thinking she is in love with Ice King. She is freed from the curse at the wedding when Jake takes off her engagement ring. Then, the Ice King accidentally marries Jake instead.
She makes her first reappearance in "Princess Day," as one of the participants in the event. This also reveals she is a registered princess.