Washington posted this video on her Instagram, showing her passing out her book to riders on the "F" train.
The memoir is titled "Thicker than Water" and documents Washington's journey of learning about her ancestry.
Washington's world turned "upside down" when she found out her dad, Earl Washington, was not her biological dad.
Her parents informed of this in 2018 as she was preparing to appear on PBS's "Finding Your Roots," a show that featured celebrities learning about their family history through DNA testing.
Instead of Washington finding out on TV, they talked to her in private and discussed with her that they turned to an anonymous donor to help them conceive after facing challenges with fertility.
"Taking this deep dive into our family history made me put myself in their shoes and think about the things that they've had to navigate and what they've been through and what they've sacrificed. And it really made me feel closer to them," Washington said.
"Thicker than Water" ties together all aspects from Washington's public life to her personal trials and tribulations.
Washington had a recent interview with GMA's Robin Roberts to talk about the book.
The interview is now streaming on Hulu.
CNNWire contributed to this report.