JAKE OWEN decided to lock down former lingerie model, Lacey Buchanan.  He proposed to her on stage Saturday night at the sixth annual Mardy's Tennis & Jake's Music Fest charity concert in Vero Beach, Florida.

Sounds like the whole thing was spontaneous.  Jake brought Lacey on stage during his song"Don't Think I Can't Love You".  They danced a little and then suddenly he went old school and dropped to one knee to propose. 


Jake even joked about not having a ring.   

Jake Tweeted, "I'm a happy man.  Life is complete."