Rose Hird, the school's head of community, said she was organising the signing up process, and 90 students were taking part so far.
"Subscription books have been given out, so people can start fundraising and making money for the cause," Hird said.
"There'll be a sausage sizzle to raise money as well."
The school's student council recently attended a World Vision conference in Wellington, which focused on leadership and "how we can help", council member Zavana Spence said.
"Poverty was better than it had ever been in history, and then Covid-19 hit," Spence said.
Fellow council member Sjoerd Molijn said they were in the process of organising "a massive group activity" for the students involved in the 40 Hour Famine.
"We are going to be using all the gyms and getting a whole bunch of people together for games and sports, it'll be great," Molijn said.
Participants have the choice to go without something they rely on (furniture, food, technology, speech) for 40 hours, and friends and family sponsor them to raise funds for vulnerable children around the world.
Two Whanganui High School students will even walk 40km over the 40-hour period.
The final part of the organisation lies with the school's heads of house, whose job it is to raise awareness.
Posters are being put up around the school, video interviews will be made, and each house will hold quizzes focused on the 40 Hour Famine.
Head of Awa Georgia Sutherland said she and fellow head Ryan Donaldson would be using social media platforms to spread awareness of the event.
"We'll be posting seven days of facts on to our different accounts," Sutherland said.
Hardy said she tried to avoid telling the students what do when it came to organisation.
"I just ask the questions and they answer them.
"It's really good that we've got such a range of stuff going on, because in a school of 1400 you want to get some diversity going."
Other local schools taking part in 40 Hour Famine fundraisers are St George's, Whanganui Collegiate, Faith City, Kaitoke, Whanganui Girls College, and Nga Tawa.
For more information on World Vision's 40 Hour Famine, go to www.worldvision.org.nz/connect/40-hour-famine/