Such was the ferocity of Jackson's punches that his much bigger opponent ended up sprawled halfway out of the ring.
Jackson, also the New Zealand professional middleweight boxing champion, said the secret to his best performance in the ring was to relax.
"The key is to relax and let everything flow," Jackson said.
"Once I got that sorted it all just came together. He was 8kg overweight for this fight so had some bang behind his punch.
"I thought I was in for a long night after that first round.
"I caught him with a nice right hook to the head and he felt that. He stumbled back on to the ropes and then dropped to the ground," Jackson said.
"He got back up and then another flurry of punches and he fell out of the ring."
The win was the next step in Jackson's journey. He hopes it will end up with the world title.
"It is another step to where I want to be and close to my dream of the world title. It is definitely the biggest career high for me and the best win I have ever had. To win the title is a bonus.
"It is a huge jump and we have been working really hard to push up the rankings. All the hard work is starting to pay off. No Kiwi fighter from the Bay of Plenty has got there."
Jackson would love to have a crack at the WBO world title held by Peter Quillan. The American is undefeated in his 30 pro fights .
"I have looked at his record and it looks pretty good. Most of them are knockouts. But before you can get to him you have to face the guys who are ranked close to him, but that's the name of the game. You have to fight the best to get to the best.
"I have only started to dream about a world title in the last year-and-a-half. I now believe in myself to get to the top and it is getting closer and closer each time I fight."
Jackson was pleased to receive support from the family of the late Tony Zale, former world middleweight champion and Boxing Hall of Famer in the US. "I was sent some photos and I am pretty stoked to know they are supporting me."
He will have a few weeks off before he gets back into serious training ahead of what could be a life-changing fight.
Chris Walker, from TGA BOX Health and Fitness, has trained Jackson since he was 18.
Walker said his fighter's fitness and work ethic gave him an advantage: "He stays fit and is always ready to go because sometimes you might get a call-up that an opportunity may arise and if you are in shape you are ready to take it.
"That is how he won his PBA light-heavyweight fight in Australia when the guy's opponent fell through. Gunnar was in good shape, ready to go, then boom."
Walker rates Jackson's win on Friday as the best he has seen from him.
"The difference was the intensity and he was sharp. Everything fell into place. He was mentally focused, he was hungry and determined. He boxed well and he did everything that he is capable of doing. Sometimes you get stuff he does sparring but he does not necessarily implement in a fight but this time it all came together.
"He really stepped it up and even I was pleasantly surprised. He changed gears up and if he puts in performances like that then he can climb further and further up the ladder."
