'The Voice' USA mentor claims he is responsible for getting his manager Brandon Blackstock, 35, to propose to the 30-year-old 'Stronger' singer last weekend after nine months together.
The 36-year-old country singer told Hollyscoop: ''I told Brandon [Blackstock], 'Man, you need to grow up and figure out that you need to marry this girl. You need to get your head out of your ass and ask that girl to marry you.
''I am going on the record saying I will do the music at the wedding or whatever [they] want to do. I'll be that guy. I will play for four hours if I have to.
''I'm so glad he did [it]. He is one hard-headed dude - and she's the best thing to happen to him.''
Kelly previously called their relationship her ''best accomplishment'' after years of being unlucky in love.
She said: ''I completely fell in love. I did! Welcome to Cheeseville! I don't know. Your priorities kind of shift and you become happier and all that stuff. It's probably my best accomplishment because I think, for me, especially, I just didn't think it would happen.''
Kelly's fiance - who is the son of her long-time manager Narvel Blackstock and the stepson of Reba McEntire - was previously married and has two children.