Semenya left Kenya's Margaret Nyairera Wambui for dead coming off the final bend to win with plenty to spare as Jamaica's Natoya Goule took bronze.
It was a challenge that proved a bridge too far in London past year, as she could only manage a bronze in the 1500m, despite again claiming gold over her favoured 800m trip.
Semenya narrowly missed the double at the world championships past year, winning the 800m but taking bronze in the longer race. We have 5,000 and 10k - I believe I can still do better in future.
South Africa's Semenya, who already had the 1500m gold in her suitcase, finished nearly two seconds clear of Kenyan Margaret Nyairera Wambui and Jamaican Natoya Goule.
Elsewhere on the Gold Coast, English tabloid darling Tom Daley captured diving gold before weighing in on gay rights, while 15-year-old shooter Anish Bhanwala became India's youngest ever Commonwealth champion.
After Semenya's double over the middle distance, Joshua Cheptegei completed a longer distance-double for Uganda, adding the 10,000-meter title in a games record 27:19.62 to go with his earlier win in the 5,000.
"There are 37 countries in the Commonwealth where it's now illegal to be who I am", he said, calling for that number to come down before the 2022 Birmingham Games.
The 27-year old has had to endure horrific treatment from athletic authorities and very bad scrutiny and speculation bordering on invasion of her privacy regarding her gender.
The night's last event, the women's 100m hurdles, was expected to be Australia's moment.
"I can't be selfish anymore, it's not just me", Adams said.
At the athletics, England's Katarina Johnson-Thompson won heptathlon gold, but New Zealand's Valerie Adams failed to take a fourth straight shot put crown, the mighty Kiwi settling for silver. World and former Olympic champion Sally Pearson featured in all the PR as the local girl but withdrew before the programme started with an injury.
"World record, we can't discuss that, it's still early, it's still April", she said.
As he approached the final water jump, he was waving Abraham Kibiwott on and then stepped out into lane two to allow his teammate the inside running, while Amos Kirui was in a battle with Canada's Matthew Hughes for bronze.
"I think it was little bit cheeky, they thought I would hang around the back", Semenya said.
The display was in honour of Australia team official Kelvin Kerkow, who did the same when he was victorious in Melbourne 12 years ago. "I'm sick and exhausted of coming here.my mentality was rewrite the script - the Kenyans just come in here and do whatever they want and nobody tries to mess up their plans".