The 53-year-old, who also won the Booker Prize in 2016, has long been a key -- if somewhat reluctant -- figure helping to bring contemporary Korean literature to global attention.
After her Booker win catapulted her into the limelight -- and triggered a surge in international sales -- Han said she would prefer people to hear her voice "in the form of writing".
"The best way is, I think, to hide in my room and start writing as soon as possible," she said.
But her Nobel immediately dominated headlines in South Korea, with Han's photo appearing on the front pages of news websites and headlines hailing her historic win -- the first by an Asian woman.
"Is this the start of K-novels?" daily newspaper Munhwa Ilbo wrote, referring to the so-called Korean wave, which has seen the country's K-pop music and K-drama television programming sweep global charts.
"She has shown K-literature to the world," it added.
Accolades poured in from across South Korean society, from the president to an ordinary book lover like Oh Ah-young, who expressed surprise at Han's Nobel win.
"I first read her works during a literature class in college and was hooked by her experimental yet sophisticated style of writing," said the gallery curator.
"Her work didn't seem representative of mainstream Korean literature at the time, around 2010, but stood out because of her unique style and distinct genre. I was really surprised by her 2016 Booker Prize win, and now I'm equally surprised by her Nobel Prize."
'Monumental achievement'
South Korean President Yoon Suk Yeol congratulated Han.
"This is a monumental achievement in the history of Korean literature and a national celebration that brings joy to all South Koreans," he wrote on his Facebook account.
K-pop megastars reacted quickly to the news, with BTS member RM sharing media reports on Han's win alongside a crying face and heart emoji.
Fellow BTS member V also shared the news on Instagram, writing: "I read your book 'Human Act: A Novel' in the army. Congratulations" alongside a bowing emoji.
Book critic Kim Seong-shin said the Academy's choice was beyond reproach.
"I'd say she is the most deserving Korean novelist to be awarded the Nobel Prize," Kim said.
Other Asian winners of the Nobel Prize for literature include India's Rabindranath Tagore, Japan's Yasunari Kawabata and Kenzaburo Oe, China's Gao Xingjian and Mo Yan, and Japanese-born British author Kazuo Ishiguro.