The powerful films feature four characters apologising to a loved one for the hurt caused by their previous ignorant or judgemental attitudes.
A quartet of 30-second films each focus on one of the identities in the abbreviation LGBT – lesbian, gay, bisexual and trans – while a 60-second version features all four characters. A 90-second cut will also be shown in cinemas.
They were created by Tian Murphy and Charlie Gee for WCRS, and directed by Fred Scott for Pulse Films. The media was handled by Jon Everare for Pride in London.
The ads will be shown during a season of programmes on Channel 4 marking half a century since the passage of the Sexual Offences Act 1967, which decriminalised sex between two men over the age of 21 in England and Wales. Gay men did not receive equal treatment under the law until the Sexual Offences Act 2003.
Sex between two women was never criminalised; lesbians were given so little consideration by the law that there was no age of consent for lesbian sex until 2000.
The campaign is the result of a partnership between Channel 4 and Pride in London. The ads will be shown on Channel 4 and More 4 from 24 June to 9 July.
Iain Walters, deputy director and head of advertising and content at Pride in London, said: "We have come a long way in 50 years, yet we face daily reminders that the global battle for true equality is far from over, and rights hard won can be threatened, attacked and taken away.
"Standing together with Channel 4, we will send a powerful and positive symbol of acceptance, support and friendship."
The main Pride event takes place on 8 July. On that day, more than 50 special guests and supporters of the LGBT community will take over the continuity announcements across all of the broadcaster’s channels, including Channel 4, All 4 and More 4.
Ross Neil, executive creative director at WCRS, added: "It’s difficult to fully appreciate the amount of love and pride that has gone into this campaign until you see the list of credits of all those who gave their time and talents to make this happen.
"This is a campaign that started from a negative place of hatred and has blossomed into a full technicolour, full volume, inclusive expression of love. The greatness of the creative is matched only by the sheer scale of companies and individuals."