Playing against a side full of talent, with a sprinkling of Black Ferns, Otago showed courage in defence and scrambled exceptionally well.
The visiting side led 12-0 at the break.
Canterbury had a sea of possession and territory, and led by hard-running No 8 Casey Robertson had plenty of opportunities.
But some outstanding defence from the home side limited the visiting side to two tries in each half.
Otago had plenty of drama during the past seven days, with coach Jonathan Homer resigning midweek, but stand-in coach Phil Young had the girls showing plenty of attitude, and they never threw in the towel.
The loss for Otago makes the road to the semifinals extremely tough for it will have to win both its remaining games, against Manawatu and Auckland, and hope other results go its way.
Looking at the coaches, it was hard to tell who had won, with Young happy with his side, while Canterbury coach Paul Kelly was far from ecstatic about his side's effort.
Young said the side had played extremely well, and had shown "some guts" in defence.
"We had done a bit of defensive work at training during the week and the girls were really receptive to it," Young said.
"At the start we weren't putting any pressure on the ball but we did more of that as the game went on and got some go forward from that.
"It's been a tough week for the girls and they showed some character out there."
Kelly was happy with the win but not much else.
He said Canterbury tried to force the ball too much and had played too much as individuals in the first half.
"We started quickly and maybe that meant we got a bit ahead of ourselves . . . we've got a lot to work on," Kelly said.
Canterbury, which just lost the final last year to Auckland, faces the Aucklanders next week in Christchurch.
Canterbury scored its opening try after 12 minutes, with former Otago first five-eighth Barbara Chittock scoring, and that was quickly followed by halfback Kendra Cocksedge going over.
Otago though stood tall with openside flanker Rachel Scott getting through plenty of tackles, as did lock Carrie Lobb.
First five-eighth Anna Richards also defended well and was harshly penalised for a head high tackle which never went above the chest.
Otago's try came with five minutes left when fullback Kelly Brazier outsprinted four defenders down the right and then put in a nice chip kick.
She then charged down the clearing kick from Tara Horsnell, gathered the ball and dived over.
Brazier was an enterprising fullback while Janna Vaughan tried hard in the Otago midfield.
No 8 Ngamamae Rapata made some good ground off the scrum, and replacement loose forward Leyhana van Vugt got round the paddock.
The Otago scrum impressed, grabbing a tighthead at one stage, and its line-out was sound.
Otago plays Manawatu in Dunedin next week.
