The 29-year-old actress revealed it when narrating her vacation in Seoul in a blog post for a leading magazine's travel diary, reported Ace Showbiz.
"On our first day in Seoul, my fiance, Michael Polish, and I venture out to discover Changdeokgung Palace. As soon as we enter, it is like magically being transported to a different world - this awe-inspiring, sprawling place was originally built in 1405," she said.
Bosworth and her director partner, who met on the set of "Big Sur", which is due out later this year, made their debut as an item at a Coldplay concert in August 2011 when they were spotted being affectionate with each other.
Prior to Polish, the actress dated 'True Blood' actor Alexander Skarsgard for two years, before ending her relationship with him in July 2011.
Skarsgard is now dating an Italian skydiver.