Actor Sir Ian McKellen and Eurovision song contest winner Conchita Wurst were among more than 20,000 people organisers estimated turned up to the Pride in London Parade today.
The event is part of the capital's week-long Pride in London festival and takes place every year to celebrate gay rights.
Today's parade started in Baker Street and will end in Whitehall, with over 200 groups from the LGBT+ community attending including Imaan (London Gay Muslims), National Union of Teachers, the Scout Association, and Gay Gooners (Gay Arsenal Supporters).
Sir Ian McKellen, 75, who came out at the age of 49 during a BBC radio interview, introduced Ms Wurst to the crowd.
She won May's Eurovision song contest for Austria with the power ballad Rise Like a Phoenix, drawing attention when she appeared on stage in Copenhagen with a full beard.
"Show business has always led the way when it comes to the freedom to be yourself," said Sir Ian.
"So, Conchita is following in the footsteps of our predecessors. There is a long tradition of outrageousness and confidence that performers embody, and that has an enormous impact. It clears the way for others to dare to be themselves. She has done just that."
Sir Ian recalled the first Pride parade he attended around 25 years ago, and said he will "never forget the feeling of being able to walk along all ages and experiences, and to finally be cheered for being ourselves."
He continued: "Today I have seen people in wheelchairs, all ages, teenagers, from all countries, and they are all proud of who we are. There are teenagers who have travelled from their own home countries to London for this, and when I see that I can say that in all honesty the world must have changed for the better. For that, I am grateful to all the old timers who pioneered the gay rights movement."
Last year's X Factor winner Sam Bailey and Coronation Street actor Charlie Condou also appeared on stage.