On a dedicated webpage, images of the fugitives are covered with masks that fall away to reveal their identities.
Europol said it wanted to highlight that women were just as capable as men of carrying out serious crimes.
Although women are perpetrators of serious crimes, statistics show the majority globally are committed by men.
A recent study on women in serious crime, commissioned by the British government and published this year, also emphasises that most criminal roles - including senior roles in organised crime groups - are dominated by men.
What is in Europol's campaign?
Of the 21 fugitives featured on the Crime Has No Gender site, 18 are women and three are men. Each person's gender is left intentionally ambiguous until their mask is removed.
Among the criminals is Elena Puzyrevich, who trafficked nine young Russian women into Cáceres in Spain and forced them into sex work.
Another, Angelina Sacjuka, is wanted for beating a young woman to death in Riga, Latvia, five years ago.
Claire Georges, a spokeswoman for Europol, said the campaign was an extension of an existing website, EU Most Wanted, launched in 2016. She said the agency aimed to increase its chances of finding the fugitives featured in the campaign.
"We wanted to show that women are just as likely to commit violent crimes as men. Even though the discourse is often around 'male fugitives', women can be just as bad," she said.
She said the agency asked EU member states to submit their most wanted female fugitives. Three states - the UK, Cyprus and Luxembourg - sent men instead.
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