The outspoken critic of president Rodrigo Duterte expressed "shock" at the award and said Rappler, the news outlet she co-founded, "would just keep doing what we're doing."
This is the best time to be a journalist. The times when it's most dangerous are the times when it's most importantMaria Ressa
"This is the best time to be a journalist," Ressa said. "The times when it's most dangerous are the times when it's most important."
Ressa and Rappler have faced multiple criminal charges and investigations after publishing stories critical of Duterte's policies, including his bloody drug war.
The former CNN correspondent is on bail pending an appeal against a conviction last year in a cyber libel case, for which she faces up to six years in prison.
Two other cyber libel cases were dismissed earlier this year.
In April, the UN's cultural agency awarded its annual press freedom prize to Ressa in recognition of her "unerring fight for freedom of expression".