The 18-year-old offspring of the 45-year-old actress and her ex-husband Tom Cruise, 62, is said to be headed to Carnegie Mellon University in Pittsburgh, Pennsylvania, and although her mom will "miss" her, she's excited for her to experience college life and find herself.
In rare comments about her daughter, she told Town and Country magazine: "I'm proud of my daughter.
"Of course, I will miss the close proximity, but I'm really proud of her and I'm happy."
The 'Dawson's Creek' alum, who has fond memories of her time at Columbia University, added: "I remember being this age, this time of beginnings.
"It's exciting to learn about yourself, and I loved that time, so it makes me happy to think about it like that."
On how her life will change, she quipped: "The members of my book club are going to get annoyed hearing from me.
"I'll be like, 'Let's meet once a week.'"
In June, Katie revealed her plans to start a new career as an author.
The 'Phone Booth' star - who shot to fame on teen show 'Dawson's Creek' in the 1990s - has branched out into writing and directing movies in recent years but she is now hoping to put pen to paper to work on fiction novels.
She told The Sunday Times newspaper: "I'd like to continue to write and direct my own films. Maybe write a few books - fiction."
Katie has been working on a number of fashion projects - including a collaboration with French brand APC - but she also hopes to eventually branch out into beauty and launch her own line.
She added: "Absolutely, I would love to [launch a beauty line]."