Putney MP and International Development Secretary Justine Greening choose the 43rd gay pride march to announce that she is in a same-sex relationship. She tweeted: "Today's a good day to say I'm in a happy same-sex relationship, I campaigned for Stronger In but sometimes you're better off out!#Pride2016".
Thousands took part in annual Pride parade through London and for the first time, the Red Arrows took part in a flypast at the march and will show support within the Armed Forces for the LGBT community.
This year's event was overshadowed by the shooting at a gay nightclub in Orlando which claimed the lives of 49 people and will have an increased police presence. A minute's silence will be led from the main stage in Trafalgar Square after the main parade.
Pride in London curator Duncan Day said: "The aim of the [Pride in London] festival has always been to provide a platform for our community to display a message, thought, argument or voice to the thousands that gather in London for our annual celebration of love, tolerance, victory and hope."
This year's campaign slogan is "No Filter". Director of Pride London, Michael Salter-Church said: "No Filter is a call to arms. A call for people to be themselves, to live as their true selves.
"Now that might sound too obvious but too many people already self-censor. On this weekend whilst we celebrate the LGBT community, be your true selves, try and live without filter because that's a really important message that we want spread around the UK and the world."
London Mayor Sadiq Khan will attend the London parade. Before the march, he said that London is "a city where the large majority of people of all communities, faiths and backgrounds, don't simply tolerate each other, but respect, embrace and celebrate our diversity".
Entertaining the crowds will be Alesha Dixon, Jake Quickenden and the Beyonce Experience.