The two civil servants are expected to become the first gay couple to tie the knot in Germany when a law allowing same-sex marriages takes effect tomorrow.
Karl Kreile told reporters the big day will be "an emotional moment full of symbolism."
In 2001, Germany became one of the world's first countries to allow same-sex couples to register for partnerships with some spousal rights.
But Chancellor Angela Merkel for years opposed same-sex marriage, only agreeing to let Parliament hold a free vote on the matter in June. A majority of lawmakers backed the move, making Germany the 23rd country to allow same-sex marriages.