Slingsby declared himself the happiest man in the world after banishing the nightmare of his Olympic Games experience four years ago to secure Australia's second gold medal of London 2012.
The 27-year-old came into the regatta as overriding favourite in the Laser class - just like he did at Beijing 2008, where he did not even make the medal race and finished in 22nd place.
Slingsby made amends this week, though, impressing throughout and securing gold in today's medal race.
'Who would be feeling better in the world right now? No one,' he said.
'I've worked for 12 years to get here. I put everything I had into it and I've done it. I couldn't be happier.
'It is a weird feeling. Last time I did everything I could to come away with a medal and I wasn't even close.
'This time around, I got the gold and I am going home very happy. Knowing all the work was for something is a great feeling.'
Knowing all the work was for something is a great feeling.
Slingsby came into the medal race with a 14-point lead over his nearest rival Pavlos Kontides, with the Cypriot taking the silver.
The 22-year-old became the first Cypriot athlete ever to win an Olympic medal.
'I guess back home they are waiting for me and when I get back there it will be huge celebrations,' he said.
'I still don't understand how huge an achievement this is for my country, being the first ever Olympic medal.
'I guess when I have the medal over my neck and when I am back home with my compatriots then I will really understand what's going on.'
Bronze went to Sweden's Rasmus Myrgren.
China's Xu Lijia claimed another gold medal for her country with victory in the Laser Radial class.
Xu, Evi Van Acker, Annalise Murphy and Marit Bouwmeester all had a serious chance of claiming the title, but it was Xu who held on while Bouwmeester took silver and Belgium's Van Acker moved ahead of Murphy in that final upwind to take bronze.
Australia, meanwhile, are set for more medal joy after Nathan Outteridge and Iain Jensen mathematically secured gold in the 49er class.
The pair got a first and third today to make their lead unassailable heading into the medal race.
They are 28 points clear of New Zealand's Peter Burling and Blair Tuke, who are assured of silver as they are 32 points ahead of Denmark.
Elsewhere, Luke Patience and Stuart Bithell moved within a point of Australian pair Mathew Belcher and Malcolm Page in the men's 470 class.
The British duo got a victory in the first race and then a sixth, which is automatically discarded as it is their worst result of the regatta so far.