The singer and dancer, 17, who found fame on the reality show Dance Moms, first alluded to the revelation on social media in a TikTok video in which she dances to Lady Gaga’s song Born This Way, which is widely regarded as an LGBTQ anthem.
The video amassed almost five million likes and 25 million views and is by far Siwa’s most popular video on TikTok.
She later posted a more definitive message, sharing a photo of herself wearing a T-shirt that reads “Best. Gay. Cousin. Ever.” and saying her cousin got it for her.
Speaking via weblink on The Tonight Show Starring with Jimmy Fallon, Siwa, 17, revealed she has "the most amazing, wonderful, perfect, most beautiful girlfriend in the whole world."
"I do have the most amazing, wonderful, perfect, most beautiful girlfriend in the whole world. It's not something I'm ashamed of, I just haven't shown the internet yet.'"
When Siwa made her announcement last month, Old Town Road rapper Lil Nas X, who came out as gay in 2019, replied: “if u spell ‘swag’ backwards, it’s ‘gay’. coincidence??”
Meanwhile, chat show host Ellen DeGeneres, who came out on the cover of Time magazine in 1997, replied with a heart emoji.
Comedian Colleen Ballinger tweeted: “I’ve known you a long time and this is the happiest I’ve ever seen you.
“You’re absolutely glowing and I’m so proud of the woman you are becoming! love yoooou!”
Siwa also reposted messages of support on her Instagram story, including one from YouTuber Tana Mongeau, who wrote: “She changed history today for the future of lgbtq youth,” and added a rainbow emoji.
Another message she reposted, from Hilton, read: “Love you @itsjojosiwa. I’m so proud of you sis!” also adding rainbow emojis.
Siwa, who has more than 10 million followers on Instagram and more than 12 million subscribers on YouTube, has become a major star with young people since she shot to fame on Dance Moms.
She signed with Nickelodeon in 2017 and has appeared in a string of projects for the network. She was the youngest contestant ever on the US version of singing competition The Masked Singer, where she was the T-Rex.