Scotland's double Olympic silver medallist made up for his disappointment in the singles at London 2012 by stunning his rivals to take gold - the first Briton to win the title. The Aberdeen-born paddler clocked 100.53 seconds, but picked up a two-second penalty for touching a gate and had to watch anxiously to see whether any of his rivals could beat him.
Eighth-fastest going into the final, another seven slalomists had to go down the course after him but none could match his time.
Slovakia's Alexander Slafkovsky took silver in 103.36 seconds with Slovenian Benjamin Slavsek capturing bronze (105.79).
Florence has a chance to add another gold today in the canoe doubles with English partner Richard Hounslow. It capped the prefect end to a frustrating season for Florence and made up for some near misses over the summer.
He said: "I knew I was in with a very, very good chance of a medal, or a good chance of maybe even holding on for the win.
"It was a nervous wait, but I had done my bit and for the guys at the top it was probably more of a nervous wait, trying to beat that time.
"It's incredible and I am very, very pleased to have come back to this off last year's disappointment at the London Games. To be world champion is the ultimate. Major championships are all different, the Olympic Games is obviously massive and it happens only every four years.
"The worlds is three out of every four years so it's more regular, but at the same time you come here and, unlike at the Games, in the world championships you have to beat the top three Slovaks, the top three French, the top three Germans.
"At the Games there is just one of each of those guys there. To be world champion is absolutely massive, it's a fantastic achievement.
"We've never won C1 in the world championships before so it's always nice to make a bit of history. Any canoe slalom race is tough to win, even if you are in great form.
"I knew I was in great form coming into it, but you can still put in a great run and end up fourth.
"It's an incredible end to the year. To have put in a lots of fast runs down this season and not quite got the results for them, then the World Cup final to be in second place, just missing out on gold, then to go one better here at the end of the season, it's absolutely spot on."