Little Mix, Kylie Minogue and Russell Brand were among the celebrities posting messages of support as Pride took place in London.
More than one million people turned out for the annual parade celebrating the LGBT community and promoting its rights.
Little Mix star Jade Thirlwall posted a photo of herself in a rainbow-striped top on Instagram, as she told fans she would always be an “ally” and would continue to support LGBT issues.
Thirlwall wrote: “To all of our LGBTQ+ fans…we LOVE you for who you are and are born to be.
“Pride is a time to come together, to celebrate and spread love and acceptance without exception whilst learning and knowing the history of why Pride exists in the first place.
“As an ALLY I promise to never stop supporting your rights, using my platform to raise awareness and challenge any form of homophobia/biphobia/transphobia.
“Also I’d like to thank @stonewalluk for welcoming me into their family and educating me on all things and teaching me what it takes to be a true Ally. HAPPY PRIDE EVERYONE.”
Pop star Minogue posted “Happy #Pride London!!” on Twitter, with heart and rainbow emojis, while comedian Brand said: “Happy #PRIDE – Lesbians, Gays, Bisexuals, trans-folk and Queers – “It’s coming OUT!”
Actor John Barrowman, who married his husband in 2013, posted a message on Twitter urging fans: “Continue to stand for what we believe in and who we are.
“Never apologize for being you.”
The star also shared a video in which he said Pride “should be celebrated everyday”.
Actor Eddie Marsan said on Twitter: “Happy #pride to all my LGBT friends.
“Your courage has enabled us all to live in a more accepting world. Proud of you.
“Now Dance!”