NASCAR's most popular driver has been dating Amy Reimann since 2009. She posted news of the engagement on Twitter with a photo of the pair in a Lutheran church where Earnhardt's family had attended seven generations and 300 years ago.
Reimann wrote she was "completely overwhelmed" with love and joy while describing herself as the "happiest girl in the world."
Earnhardt then reposted the picture, adding: "Looking forward to the rest of my life with this amazing girl."
Earnhardt has been giving fans a thorough play-by-play of his trip to Germany and where his family emigrated from in 1744. His sister and brother-in-law are also on the trip.