Canada led 9-6 at the half and added some early insurance in the second half with Dala's try.
But Namibia star Jacques Burger, who plays for Saracens in England, rumbled over the line for a converted try with five minutes remaining to make things interesting at Parc Eirias in north Wales.
"It's a win in a test match and we finally got over the line in one which is good," said Canadian coach Kieran Crowley. "Heart in the mouth a little bit towards the end but Namibia put a lot of pressure at the breakdown
"We had a lot of opportunities. There'll be a lot of good learning from the video footage of that game, I would think ... Now we have something to build on going towards (the game against) Samoa."
Gordon McRorie kicked four penalties for Canada. Theuns Kotze booted two penalties for Namibia.
Jordan Wilson-Ross came off the bench to earn his first Canadian cap.
"We gutted it out," he said. "It was kind of sloppy at times but we pulled it together, did what we had to do ... and got the win."
Canada is ranked 17th in the world, compared to No. 22 for Namibia. The win ended a string of four straight losses this year for the Canadians, whose last victory was a 52-8 decision over Portugal in Lisbon last November.
Both Canada and Namibia are headed to the World Cup next year, albeit in different pools. Namibia is the only one of the 20 teams at the 2015 tournament that has yet to win a game at the rugby showcase.
In the only previous meeting between the two, Canada thumped Namibia 72-11 at the 1999 World Cup.
The Canadians head to France next to take on No. 9 Samoa in Vannes on Nov. 14 before wrapping up the tour Nov. 22 in Bucharest against No. 16 Romania.
Canada and Romania are both in Pool D at the World Cup, along with No. 5 Ireland, No. 7 France and No. 14 Italy.
The Canadian men opened their tour with a 28-23 loss last Saturday to an RFU Championship XV side in Worcester, England.Suggest a correction