Fairweather, who was only the fifth fastest qualifer and started in lane 2, lingered in fourth place for much of the journey. But she mustered a strong finish and powered past Englishwoman Freya Colbert as they headed for home.
Her time was 1min 55.24s, more than three seconds faster than her qualifying effort. She beat Colbert by half a second. The race was won by Australian Mollie O'Callaghan in 1min 54.66s.
Fairweather was bubbling afterwards. 'I’m proud with that effort. That was a super competitive final, so to be right up there is awesome.'
Ouwehand swam brilliantly to secure her medal. The race - a chaotic splash and dash - was won by Australian Alex Perkins in 25.37s. Ouwehand recorded 25.76s and had room to spare over fourth-placed South African Jessica Thompson, who was timed at 25.92s.
'Wow, yep, I’m happy with that,' said the 26-year-old Aucklander. 'In the final moments you’re just putting your head down, pushing hard and trying to get every last inch out of your touch.'
Meanwhile, neither New Zealand woman in the 100m backstroke semi-finals was able to progress to the final.
In the semi-finals, Amber George recorded 1min 01.24s, which placed her 11th overall and Savannah-Eve Martin was timed at 1min 01.35s, 12th overall. The fastest qualifier was Canadian Kylie Masse in 59.71s.
Martin said she was happy with her swim. 'It's not my best, but it was faster than I did this morning. I gave it everything I had and I'm proud of my effort.'
New Zealand just missed another medal when they finished fourth in the mixed 4 x 100m freestyle relay. The New Zealand team of Carter Swift, Cameron Gray, Chelsey Edwards and Fairweather were briefly third in the middle stages of the race but were overhauled by Wales and placed fourth. Australia won the race in 3min 19.36s. New Zealand swam a national record of 3min 24.82s but missed the bronze by half a second.