The couple - who met whilst starring on 'Game of Thrones' together - have posted a notice at Huntly registration office in Aberdeenshire, Scotland, which is 15 miles from Leslie's family home of Wardhill Castle.
The notice also reveals that the couple plan to wed on June 23, the Evening Express reports.
Kit and Rose announced their engagement in the Forthcoming Marriages section of The Times newspaper last September.
The notice read: ''The engagement is announced between Kit, younger son of David and Deborah Harington of Worcestershire, and Rose, middle daughter of Sebastian and Candy Leslie of Aberdeenshire.''
Kit had previously revealed that he had asked producers to shut down filming on 'Game of Thrones' final season so his castmates could attend their big day.
He said: ''I rang up [the producer] and I said, 'I'm getting married and it's your fault actually'... I think for the final season he is so stressed that he's reached that peaceful level. I was like, 'You need to factor in a 'Game of Thrones' wedding by the way.' They have all got to be there so the whole thing has got to shut down.''
Now the pair are set to tie the knot, Kit says he could never work alongside Rose again.
He explained: ''I wouldn't be able to keep a straight face. Honestly, I was watching Sliding Doors with her the other day, and there's a bit at the end where John Hannah is pouring his heart out to Gwyneth Paltrow and she's lying dead. I turned to Rose and I said, 'I wouldn't be able to do that with you, because you would piss yourself.' She's a brilliant actor. Actually I don't want to work with her because she would just show me up again. That's why.''