In these areas people will be "encouraged" not to smoke or vape.
Council-owned facilities will also become smoke and vape-free under the policy, as will council-funded events.
Vaping - inhaling vapour produced by an electronic device - is on the rise as an alternative to smoking and mayor Hamish McDouall believed Whanganui was the first council in the country to include vaping so prominently in a smokefree policy.
Safer Whanganui's Lauren Tamehana demonstrated vaping for councillors at last week's submissions on the policy.
Medical professionals and community groups raised concerns about vaping which prompted council to add it to the policy, Mr McDouall said.
"I personally find the range of sweet, candy-related flavours so cynical, especially when you hear that buyers are literally then asked whether they'd like free nicotine with that," Mr McDouall said.
"Although the evidence isn't conclusive that vaping is a gateway to cigarette smoking, I have heard of young people who have become nicotine-addicted through vaping and then transitioned to cigarette smoking."
At the submissions on the policy Dr John McMenamin said vaping as an alternative to cigarettes needed to be treated with caution.
"Long term there is definitely going to be some risks associated with vaping as well," he said.
"There are harm reduction benefits but there are significant health risks associated with it."
Scott Vickers from The Mushroom Cloud on Victoria Ave, which sells vaping liquid and equipment, didn't think the new policy would impact on vapers too much.
"At the end of the day it's not the same thing but I don't oppose it either," he said. "I'm going to continue vaping in my shop."
He said he was already conscious about where he vaped in public.
"It's more courtesy I guess. Non-smokers see it as the same thing.
"I can't speak for anyone else, I can only say what I see out the shop. I think at the end of the day you'll have people that just do it (smoke and vape anyway)."
Ms Tamehana said vaping in public spaces normalised smoking behaviour.
"There are a whole range of views on vaping, including that it can assist people to stop smoking cigarettes.
"While that may work for some people, the view of Safer Whanganui is that on balance a vaping habit is likely to have negative health impacts long-term and actually contribute to the smoking culture we are working very hard to address."
Councillor Charlie Anderson supported the council's new policy which encouraged people not to smoke or vape within 4m of entrances and exits of all public buildings in public areas.
"I started smoking young and was addicted within a very short time," he said.
"I know exactly how powerful this is and how hard it is to give up. Thankfully I have kicked the habit, but I'm only ever one cigarette away from starting up again."
"Anything this council can do to reduce the number of smokers in our community and the impact of smoking on our environment is something I want to support."
