In the film, premiering on Thursday, Adams plays a linguist hired by the US government to go inside one of 12 spaceships that have touched down around the world.
Her task: to establish contact with the extra-terrestrials on board, develop a common language and discover the purpose of their visit.
The movie, which also stars Forest Whitaker and Jeremy Renner, is one of 20 US and international films vying for the Golden Lion that will be awarded on Sep 10.
Various scenes in the movie are silent, with Villeneuve using close-ups of Adams to convey that real communication does not always require words.
"I was drawn in by the intimacy of it," Adams told Reuters.
She said she always asks directors why they want her for a part, and turns down roles where they are looking for "someone to be likeable".
"Denis said 'I need to know what she's thinking'... He trusted the audience to go on this emotional journey," she later added at a news conference.
"Arrival" is one of several movies in Venice that feature a strong female lead.