In an interview with Oprah Winfrey set to air on Monday night, the first lady says the election has reinforced her view that her husband's administration was able to inspire hope "because we feel the difference now".
"Now we're feeling what not having hope feels like," she says. "You know? Hope is necessary. It's a necessary concept. And Barack didn't just talk about hope because he thought it was just a nice slogan to get votes. I mean, he and I and so many believe that if you ... what else do you have if you don't have hope?"
"What do you give your kids if you can't give them hope?" she added.
Mrs Obama sat for the interview five weeks after the election of Donald Trump to the White House.
The Obamas campaigned aggressively against Trump and argued that the New York businessman is unfit to be president.
CBS released an excerpt of the interview on Friday. In it, Mrs Obama does not mention the incoming president by name.
While Obama has refused since the November 8 election to repeat his criticisms of Trump, Mrs Obama comes off as less accepting of the outcome.
In the interview, which was taped on Wednesday in the White House residence, she said the public will eventually appreciate what a reassuring presence her husband was during the past eight years.
She compared him to the person who doesn't freak out when a toddler bumps his head, causing the child to start crying.
"I feel that Barack has been that for the nation in ways that people will come to appreciate," she said.
"Having a grown-up in the White House who can say to you in times of crisis and turmoil, 'Hey, it's gonna be OK. Let's remember the good things that we have. Let's look at the future. Let's look at all the things that we're building."'
"All of this is important for our kids to stay focused and to feel like their work isn't in vain. That their lives aren't in vain," Mrs. Obama added.
"What do we do if we don't have hope, Oprah?"