The former presidential candidate will release her untitled tome on 26 September, says Simon & Schuster. Financial terms were not revealed.
The publisher said Mrs Clinton will use some of her favourite quotes to "tell stories from her life".
The Democrat lost the election to Republican Donald Trump in a stunning upset, even though she won more votes.
"These are the words I live by," former secretary of state Mrs Clinton said in a statement of her forthcoming book.
"These quotes have helped me celebrate the good times, laugh at the absurd times, persevere during the hard times and deepen my appreciation of all life has to offer.
"I hope by sharing these words and my thoughts about them, the essays will be meaningful for readers," she added.
The 69-year-old is also resuming her relationship with the Harry Walker Agency, the speakers' bureau she left in 2013 as secretary of state.
Her money-spinning career as a speaker, including talks sponsored by Goldman Sachs, were a festering subject of criticism from political opponents.
She is set to speak at an International Women's Day event next month organised by Vital Voices, an organisation founded by Mrs Clinton and then-Secretary of State Madeleine Albright in 1997.
The event was not organised by the Harry Walker Agency, according to Clinton spokesman Nick Merrill.
Her plans to return to that agency are seen as making it unlikely that she might launch a bid for the mayoralty of New York City, as Clinton-watchers have speculated.
She is also set to appear at an LGBT community centre gala in New York on 20 April and deliver the commencement address at her alma mater, Wellesley College.
Mrs Clinton has kept a low profile since the election, but attended Mr Trump's inauguration last month and has criticised his policies.
Hillary Clinton is writing a book of personal essays, including reflections on last year's US election.