The director has shot a video message to locals asking them to bear with him and his cast and crew as they "mess up" the city in the coming weeks.
He says, "I'm really grateful and excited to be filming in your city. We are going to mess it up a bit and inconvenience some people for a few days and I apologise for that.
"I know what that's like; I live in Los Angeles (and) it happens to me all the time, and it's not fun. I hope that it will be worth it."
Whedon and his Avengers army arrive in Seoul after shooting in South Africa and Italy.
The Avengers: Age of Ultron is due for release next year (15).