During the performance, Carey donned four outfits as she performed some of her hits to a crowd of approximately 50,000 fans.
The first two were blue pink and white/silver – a nod to the colours of the transgender pride flag.
She also wore a jacket with the phrase “Protect the Dolls” emblazoned on the back.
She dedicated her song Hero to the LGBTQ+ community, saying it had been there for her for so long, supporting her through good and bad and that she would always be there for them.
What followed was the Park singing along to the classic song in unison.
From the scene, BBC Radio Sussex reporter Anthony Martin said some fans had dressed up in Christmas attire hoping to hear one certain song by Mariah – but this one was not on the set list.