The Canadian sisters, who are both gay, were an inspiration to Kiyoko as a kid coming to terms with her own sexuality.
And she says their support has been vital to her since coming out in 2015, as they have helped her cope with the pressures of being an openly gay popstar, and an icon to fans.
"I love them so much," she tells Billboard magazine. "They mean so much to me because they've reached out and let me know that they love me and that they support me for who I am, and it's meant so much to me."
"They are kind, and intelligent, and hard-working, and they care about other artists just as much as themselves," she continues. "I think that that is so powerful, and I'm very appreciative of their support."
The "Closer" hitmakers have also been big supporters of her music, tweeting about their love for her debut album "Expectations" in 2018.
"I thought WE were the "unapologetically queer pop stars" the world was waiting for? JK. (joke from the article below) We are OBSESSED with @HayleyKiyoko," they tweeted ahead of its release. "She's bada**. So talented. And truly IS an unapologetic queer pop star you've been waiting for."