She first appeared in 2025 saving an airliner from falling to it's destruction saving it and the people on board. when questioned superman had said "can't wait to see my cousin in action"
soon she did more and more eventually also appearing in public and allowing for interviews. eventually she revealed that she had a few run ins with other heroes like spider-man and even batman and robin, but is very good friend with batgirl.
when she first appeared people's reactions were mixed, some saying she wouldn't do good, and others saying she'll be another superman. Soon she managed to proove herself and even managed to gain acclaim. the #Supergirl trend skyrocketed at this time and she was just as accepted as her cousin.
Recently Rumors have sprouted up about Supergirl being in a romantic Relationship with fellow superhero Spider-Man, when asked about these she refused to comment.