Hyeonseo Lee, 37, told Fox News on Wednesday that Trump's stern approach resonated with her and other defectors who endured famine under the authoritarian regime.
"Not any president said those words until today even though we've been suffering for seven decades," Lee said, adding that she cried when she heard Trump's tough talk.
Since assuming office, Trump has frequently tweeted about North Korea and has said Pyongyang is "looking for trouble" and has been "behaving very badly."
But the president's remarks have also been wide-ranging.
Lee, who gained international fame with her memoir and a TED talk, did not provide comments on those recent quips from Trump.
But the author of The Girl with 7 Names did say the regime is one of the world's worst.
"The North Korean regime really can control people," Lee said. "I think they are the best dictator in the whole planet."
Lee said she escaped North Korea in 1997 at the height of a disastrous famine that killed more than a million North Koreans.
She lived the life of a fugitive in China before defecting to South Korea.
"Because of so many dead bodies, certain people's job was to get rid of the bodies, with carts," Lee said of her past life in North Korea.
Defectors have been warned against traveling overseas after the assassination of Kim Jong Nam, the older half-brother of the ruler, in February.