Piers Morgan believes women taking part in Januhairy are "lazy and revolting" for not grooming themselves to a level he says men find attractive.
The 53-year-old British broadcaster made the comments both on Twitter and TV show Good Morning Britain.
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Morgan also said his shaving standards only apply to women and that men, such as himself, aren't revolting if they don't comply.
"Men don't fancy women who let it all out in January, trust me," he said in the broadcast.
When Good Morning Britain co-host Susanna Reid asked if he was also being lazy and revolting by not shaving his armpits, he said "no, because women don't have a problem with that".
Morgan also said that something inside him died when he saw a photo of Julia Roberts with hairy armpits.
Januhairy was launched by British university student Laura Jackson, who is using the month much like Movember to raise money for a body-positive education programme.
"When I first started growing my body hair my mum asked me, 'Is it you just being lazy or are you trying to prove a point?'" Ms Jackson wrote on Instagram.
"Why should we be called lazy if we don't want to shave?"
Replies to Morgan's tweet are mostly jokes, although tabloid The Mirror reports his comments "triggered outrage".