The pair are the children of president George W. Bush, who held office from 2001 to 2009. Though they never lived in the White House (they were attending the University of Texas and Yale, respectively) they regularly visited their parents in Washington.
Malia and Sasha are set to move out of the space they've lived in since 2009 on Friday, Jan. 20, the day Donald Trump is inaugurated as president.
"Now you are about to join another rarified club, one of former First Children -- a position you didn’t seek and one with no guidelines," Jenna and Barbara wrote in Time. "But you have so much to look forward to. You will be writing the story of your lives, beyond the shadow of your famous parents, yet you will always carry with you the experiences of the past eight years."
They went on to tell the girls to stay in touch with the folks who helped raise them during their time in Washington.
"They were part of growing up for us: there for first dates, first days and even an engagement and a honeymoon. We know it wasn’t always easy -- the two of you and the two of us were teenagers trailed by men in backpacks -- but they put their lives on hold for us."
Jenna and Barbara wrapped up the letter by commending the girls for their composure when times during their father's presidential term were tough.
"You have lived through the unbelievable pressure of the White House. You have listened to harsh criticism of your parents by people who had never even met them. You stood by as your precious parents were reduced to headlines. Your parents, who put you first and who not only showed you but gave you the world. As always, they will be rooting for you as you begin your next chapter. And so will we."
The Obama girls certainly have bright futures ahead of them. While Malia is set to take a gap year before heading to Harvard, Sasha will focus on wrapping up high school.
This wasn't the first time the Bush sisters wrote a letter in support of the Obamas. In 2009, as Barack was inaugurated as president, they penned an op-ed in The Wall Street Journal.
Read the full letter here.