"If Year 13 students are allowed to wear mufti, how come they are not allowed to have natural hair that grows on their face?" McEwen wrote.
"I want to get enough support for my petition so I can show the board of trustees that there is nothing wrong [with] having facial hair."
McEwen said Year 13 students should be able to have facial hair so they could "express who they are".
Facial hair could also be used to hide scars or "embarrassing things" on students' faces, he said.
"Women are allowed to wear makeup to hide scars or specific things on their faces, so how come males are not allowed to do the same with natural-growing hair?"
The petition, started a month ago on website change.org, has gathered 353 signatures.
Upon reaching 500, it will be delivered to board member Tony Kane, according to the website.
Many signees have shared messages of encouragement.
"I believe the school rules are to create conformity which in turn helps control the masses," Wellington woman Yvonne van Leeuwen wrote.
"That said, many of the rules were formed a long time ago and could do with review. Good on Anthony for bringing this one to public attention."
Kapiti coast woman Sarah Rickard wrote: "Year 13 is an option and so is facial hair."