Chelsea Clinton and her husband, Marc Mezvinsky, are expecting their first child later this year.
The 34-year-old daughter of former President Bill Clinton and ex-Secretary of State Hillary Rodham Clinton made the announcement Thursday at the end of a Clinton Foundation event in New York on empowering girls.
Joined on stage by her mother, Chelsea Clinton said she feels "all the better whether it's a girl or a boy that she or he will grow up in a world with so many strong female leaders."
"I just hope I will be as good a mom to my child and hopefully children as my mom was to me," the former first daughter said.
The former first lady, secretary of state and New York senator, who is considering another presidential campaign in 2016, said she was "really excited" about becoming a grandmother.
"It makes this work even more important because we've made a lot of progress," Clinton said.
"I want to see us keep moving and certainly for future generations as well so that maybe our grandchild will not have to be worried about some of the things that young women and young men are worried about today," Hillary Clinton said.
Chelsea Clinton said in an interview with Glamour magazine last year that she and her husband were hoping to start a family soon, calling 2014 "the year of the baby."
The younger Clinton is vice chairman of the Bill, Hillary & Chelsea Clinton Foundation, which was previously known as the William J. Clinton Foundation. Chelsea Clinton has taken a leading role in the organization, helping direct its humanitarian and philanthropic efforts around the globe.
She has avoided commenting on her mother's potential presidential campaign except to say that she'll support her in whatever she does. But she would be a strong voice for her mother among young voters if the former secretary of state decides to seek the presidency.
After the announcement, Bill Clinton weighed in on Twitter: "Excited to add a new line to my Twitter bio...grandfather-to-be! @HillaryClinton and I are so happy for Chelsea and Marc!"