Y. S. Lee is a notable author born in Singapore, and raised in Vancouver and Toronto. She spent some time living in England where she completed her PhD in Victorian literature and culture. It was during her doctoral research that she began crafting a story about a girl detective in 1850s London, which laid the groundwork for her debut novel, The Agency: A Spy in the House. This novel not only launched her writing career but also won her the Canadian Children's Book Centre's inaugural John Spray Mystery Award in 2011.

Lee's writing continued with The Agency quartet, which includes The Body at the Tower and The Traitor and the Tunnel, both receiving nominations for prestigious awards. The fourth installment, Rivals in the City, concludes the series. Her books have been celebrated for their gripping narratives and have been published by Candlewick Press in the U.S. and Canada, and by Walker Books in the U.K. and Australia, and translated into French and German.

In addition to her novels, Lee has achieved recognition for her poetry. Her poems have won CV2's 2022 Foster Prize and been finalists for awards in Canada, the U.S., and Australia. She published her first chapbook, Exit Permit, with Anstruther Press in 2023, and her lyric essay, "Tek tek", was shortlisted for the 2022 CBC Nonfiction Prize. Lee's first picture book, Mrs. Nobody, is set to be published by Groundwood Books in 2025.

Lee, also known as Ying by her friends, is an immigrant and settler residing in Kingston, Ontario, where she engages with the local history and culture.