Australian paddling great Jess Fox has won the 21st world championship medal of her unparalleled career - but the 13-time slalom canoeing champion had to settle for the canoe bronze at the sport's showpiece event in London.

Penrith's Olympic champion in the C1 event paid for an early mistake in her final run at the Lee Valley Whitewater Centre and ended up finishing third behind the British pair of gold medallist Mallory Franklin and second-placed Kimberley Woods.

It was a close-run affair with 29-year-old Fox the fastest to complete the course in 106.94 seconds but the two penalty seconds she gleaned from touching the third gate meant she lost out to the home duo - Franklin by 0.89 and Woods by 0.47- who both had flawless runs.

It was yet another medal in the remarkable career of the woman considered the greatest paddler of all but 10 years since she took the first of her four world C1 titles, Fox always measures success in gold, having previously amassed 13 titles in all.

Of her 21 medals won over a span of 13 years, this was only the third bronze.

"It's been a pretty crazy world champs so far, I didn't have the best start in C1 so making the final and getting that Olympic quota spot, that was the goal," Fox said.

"To come away with a medal is awesome although I am a little bit frustrated with my touch which kept me off the top step but it's still awesome to come away with another medal."

After taking gold in the kayak team event earlier in the week, Fox still has a chance to strike gold number 14 in Saturday's individual kayak final, for which she qualified in second place.

Set to head to her fourth Olympics in Paris next year, Fox said she felt "quite emotional".

"It's been a big build-up and it's never easy to go and get a quota and it was super tight racing this morning so to get that out of the way I'm really relieved.

"I'm thrilled to be heading to Paris."