The "Bon Appetit" singer laid it all out there during Monday night's primetime special, after the host asked her about her "Taylor Beef."
"There's a situation. Honestly, it's like she started it and it's time for her to finish it," Perry said, adding that the whole situation was all "about backing dancers."
"It's so crazy," she added.
"It's about 3 backing dancers that went on tour with her tour and they asked me before they went on tour if they could go," Perry said. "And I was like, yeah of course, I'm not on a record cycle and get the work and she's great but I will be on a record cycle in about a year, so be sure to put a 30-day contingency in your contract so you can get out if you want to join me when I say I'm going back on."
"So that year came up and I texted all of them because I'm very close with them and said, look, just FYI, I'm about to start, I want to put the word out there," Katy said. "They said OK, we're going to talk to management about it and they did and they got fired."
Perry said she tried to call up Swift herself and hash it out, but "she wouldn't speak to me."
"I do the right thing, any time it feels like a fumble," the singer added. "It was a full shutdown and then she writes a song about me, and I'm like, 'OK, cool, cool, cool, that's how you want to deal with it?' Karma!'"
"But what I want to say is that I'm ready for that BS to be done," she went on. "Now, there is the law of cause and effect. You do something and there's going to be a reaction, and trust me, daddy, there's going to be a reaction."
Corden then asked if it was possible to "take the beef off the grill."
"I think personally that women together, not divided, and none of this petty bullshit, women together will heal the world," Perry said.
The host then wondered if it would "be enough" to get a text from the "Shake It Off" singer saying "the beef is off the grill."
"One hundred percent," said Perry.
The segment ended with Corden vowing to "get to the bottom of this."
The public feud between the two started when Taylor told Rolling Stone that her chart-topping single "Bad Blood" was about a fellow pop star who backstabbed her. "She basically tried to sabotage an entire arena tour," Swift said back in 2014. "She tried to hire a bunch of people out from under me."
Earlier this month, Katy released a track of her own many assumed was about Swift, "Swish Swish."
Amid the speculation that the song and "Witness" were responses to Swift's "Bad Blood," Perry told Entertainment Weekly that "there is no one thing that's calling out any one person."
"It’s really quite brave. Sonically, it’s fun and dance-y and dark and light. It’s all of these things. It definitely is a change," she said.