Singapore's Pink Dot rally started in 2009 and has historically attracted crowds of up to 28,000 despite a backlash from conservative groups in a state where protests are strictly controlled.
But those taking party in this year's rally, which promotes 'freedom to love', had to show identity cards to prove they were citizens or permanent residents before being allowed into a barricaded zone.
They included both gay and straight Singaporeans, families with small children and Muslim women in veils, with many sitting on picnic mats under the scorching sun.
"It's disappointing because we went from marching in London Pride last year right behind (London mayor) Sadiq Khan to having to celebrate separately," she told AFP.
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Organisers declined to issue a headcount for the event but an AFP reporter estimated about 8,000 people were already in the park when the three-hour event started at 5pm (local time). It was full within two hours.
It culminated in a rainbow-coloured formation with torchlights after dark.
Apart from a ban on foreigners attending this year's rally, overseas companies were also banned from providing sponsorship.
Multinationals like Facebook, Google and Goldman Sachs had funded previous editions as part of their equal- opportunity initiatives.
Under a law dating back to British colonial rule, sex between men is technically still a criminal act in Singapore but the statute is not being actively enforced.
Open support for gay rights has meanwhile grown in recent years, aided by changing social norms among the younger generation and a large influx of tourists and expatriates.