SUPERGIRL 1x08 Clip - Cat Discovers Kara's Secret (2015) Melissa Benoist Calista Flockhart CBS HD 

@Deon Bailey in S2 cat knows she is Supergirl when she excuse herself after Mon El heartbreak

That probably not! Reminder j’onn didn’t reveal to the world he is a shapeshifter yet! Cat knew because kara kept doing stuff that cat say to her it can’t be a coincidence of what she did!

yes she actually still knew… spoilers last episode of S6 which is the final episode of the whole supergirl series, cat grant actually called kara and she told her that she was supergirl. this proves that she knew and kept it secret for over 6 years

Well…ur were right after 6yr this came true.

I think Lena did suspect something the first time they met which is why she used the alien detection device on Kara (the one she used on Rhea later) to see, and when it came back negative she stopped wondering.

Annabelle Sanchez Well the thing is, she still knew! She always knew... she especially was certain after learning about shapeshifting Martians in central city... she will surely know about Hank and Jonn as the queen of all media right? She just decided to leave Kara in peace seeing how much effort she will take to trick her... she gave her her privacy and pretended not to know from then on.