The two filmstars have been dating for over two years but want to wait before tying the knot, she said in an interview.
Asked for a wedding date, Kareena, 25, said, "Not for the next four years for sure."
"I'll most definitely marry Shahid, I'm not the kind to jump from one relationship to another," she said in the interview.
"For me, love is for keeps."
The popular actress, who has three Filmfare awards to her name, did not say why the couple plans to wait.
Despite their off-screen romance, the couple's on-screen chemistry has failed to ignite most audiences - they starred together two years ago in a thriller Fida which bombed at the box office. Their latest on-screen pairing in the film Chup Chup Ke was released in June 2006.
The two recently walked down the ramp together at the Indian Fashion Week held in Delhi in September.