His teachers were "ecstatic".
"I've had an amazing school with really supportive teachers who enabled me to get to where I want to go."
About 300 students a year get a perfect score, he said.
Samuel isn't sure yet what he wants to major in but will probably end up studying economics or political science.
"Probably law later on, because you can't do law at the undergraduate level."
Samuel gained a Te Ara a Kupe Beaton scholarship in year 11, which he was awarded by Crimson Education.
He credits this scholarship with giving him the skills needed to apply for Harvard.
The scholarship is given to young Māori students "who have the spirit to conquer the world stage".
It includes $20,000 of academic mentoring, extracurricular advice and career advice, with the goal of enabling recipients to enter top universities in New Zealand and around the world.
Samuel encourages high school students to apply early if they want to study overseas.
"Some kids don't apply until year 13 ... you do have to start early, and make those decisions really early on to start building up that profile for the American universities," he said.
"It's been a fantastic experience."
Samuel said he was most looking forward to "a white Christmas" for the first time in 2020, but the prestige of Harvard was definitely on his list of things to look forward to.
He says there will be challenges as well.
"That's what makes it the best school in the world, is if it's a challenging place where you have to drive yourself to do better," he said.
"I'm looking forward to it though ... challenge is exciting."
Despite not being sure what he plans to major in, he knows he wants to enter politics at some stage after he graduates in 2024.
"For the time being, it'll probably be business ... or law.
"That's one of the real advantages of the American liberal arts degree ... you actually get a year or two to figure out what you want to do and what you're passionate about," he said.
"Down the line, the end goal is politics."