He was thrilled with his performance, saying: "I am ranked 50th in the world and here I am sitting eighth at the Olympics.'
Top qualifier was Germany's Hannes Aigner.
Dawson, 25, punched the air after his second run, knowing he was through to the next round.
"To make the final, I need to be cleaner. The speed is there, which is something I wasn't sure about today but just don't hit the gates."
The top 10 go through to the final with the medals also decided on Thursday morning (NZT).
---------------
EARLIER STORY: Local paddler Mike Dawson has qualified for the semifinals in the men's kayak slalom at the London Olympics.
Dawson finished in eighth place in the heats with the top 15 progressing to the next round which takes place on Thursday.
Dawson sat in eighth after the first run with a score of 90.90 and improved in his second run with the sixth best score of 88.58.
Germany's Hannes Aigner leads the field.
Meanwhile, Rotorua rower Julia Edward and her lightweight scullls partner Louise Ayling missed automatic qualification.
They finished third in their heat, forcing them into a repechage Tuesday night (NZT). They were beaten by Great Britain and Denmark, crews they had defeated in both World Cups during the European season. They secured silver and gold medals at those regattas in Lucerne and Munich, respectively, but pre-Olympic results can flatter to deceive.
Adding to their frustration will have been the slower times in the other two heats. New Zealand finished in 7.02.78, 5.81s behind Britain, while Greece won the second heat in 7m 03.66s and China won the third in 7m 15.57s.
However, little can be read into comparing heats. Conditions can change quickly and times alter accordingly.
The New Zealanders were the quickest through the first 500m, moved to second behind Britain over the middle 1000m before the Danes caught them towards the end.
"We were pleased with the start, happy with our boat speed through the middle but in the last 600-700m we may have gone a bit early trying to hold them [the Danes] off," Edward said.
- HERALD ONLINE/APNZ