The 22-year-old Nel-Peters has earned a year-long salary, a luxury apartment in New York City for the duration of her reign and more prizes.
Although Ms Atarangi Ihaia, did not make it into the top 16, executive director of Miss Universe NZ Nigel Godfrey said he could not be prouder of the 19-year-old and the way she conducted herself.
"Although only one contestant takes the title we consider that there are 92 winners. Harlem has embraced every aspect of her journey so far and she is everything that Miss Universe New Zealand would want in a title-holder.
"She entered the competition to break stereotypes and she has done just that - opening up the possibility of entry to a whole new area of the country," Mr Godfrey said.
"After a well deserved holiday, we are really looking forward to getting her back to NZ and continuing what is going to be a great year of her reign as Miss Universe NZ 2017."
Ihaia, a kohanga reo teacher and the first New Zealand contestant to wear tā moko - a permanent marking similar to a tattoo on her left shoulder - has spent the last couple of weeks in auditions, photo shoots and touring Las Vegas.
She paraded as The Goddess of Fire for her national costume, which featured black feathers "representing the misperceptions that shadow her indigenous people," MC Nia Sanchez stated.
During this, Ms Sanchez mistook her for Ms Netherlands, noting, "With a strong desire to be The Goddess of Fire, it's Netherland... New Zealand."
In a post on her Facebook account on Sunday, Ms Atarangi Ihaia said she had never focused on winning, but rather "focused on the journey and taking every opportunity and just going with the flow".
"The meaning of winning is a bit different for me, it's not just about the title and the crown. It's about leaving here knowing I've done beyond my best to represent myself and my country, leaving here a changed woman, having new friends from all around the world, being confidently beautiful being myself, and last but not least having the best memories of being Miss Universe New Zealand at Miss Universe here in Las Vegas and enjoying this once in a life time opportunity. So basically there's no way I can lose."