“I’m absolutely thrilled, I’m in shock – being shortlisted in itself was a huge honour,” she told the BBC.
Her winning short story is about an Ethiopian boy called Getu, who has to navigate the fraught power dynamics of NGOs and foreign aid in Addis Ababa.
It impressed the judges who found it “utterly without self-pity” and said it “turns the lens” on the usual clichés.
Hadero will take home £10,000 ($13,000) in prize money.
The author was born in Ethiopia and raised in the US by parents who are both medical doctors. Her sister is the singer Meklit Hadero, whose support was “absolutely essential” to her success, Hadero says.
She says stories of “refugees, immigrants and those at risk of being displaced” are always the “entry-point emotionally” to her work.
“With The Street Sweep, he has that threat looming. He’s facing losing his ancestral home, and that’s the real driver of the story that makes him take charge and try to re-write that outcome that seems kind of inevitable,” Hadero told BBC Focus on Africa.
Much of The Street Sweep is set in Addis Ababa’s Sheraton hotel, where Getu is invited for a party.
“Looking through his eyes it’s almost a culture shock when he goes there,” Hadero said.
“I did want to paint that contrast… What does that access mean? And what does that bestow? That’s the bigger question of what those open doors represent.”
Writing short stories has been “it’s own love” for the author, who likened the form to a “contained laboratory” from which “pared down and elegant” tales can emerge.
Her next challenge is her debut novel, which “is really fun to work on in a different way.
“You’re adding and you’re exploring mess.”