The New York Post's Page Six reported the elevator doors then shut, but a punch was audible.
Aside from a break to give a talk at the Oxford Union at 8pm and brief exits to visit the toilet, LaBeouf spent 24 hours in the lift.
He started at 9am on Friday and remained in the lift until 9am Saturday.
Viewers were able to watch the performance in a live YouTube stream entitled #ELEVATE.
The Hollywood star was joined by friends and musical collaborators Nastja Ronkko and Luke Turner, as well as other visitors to the building.
The Union wrote on its YouTube site: "Visitors will be able to join LaBeouf, Ronkko and Turner inside the elevator during this time, and are invited to address the artists, the debating chamber, and the internet, so that their collective voices may form an extended, expansive and egalitarian Oxford Union address."
Union events are usually only open to members, who must be students or alumni from the University of Oxford or Oxford Brookes.
LaBeouf has sent a precedent for the stunt with a number of other performance art pieces.
The 29-year-old set up his own call centre in Liverpool, where members of the public could phone to ask him questions.
In 2014, in response to being accused of plagiarism he wore a paper bag over his head with the message "I am not famous any more" and sat in a Los Angeles art gallery, where members of the public were able to interact with him.
For another event, called #ALLMYMOVIES, LaBeouf rented out a small cinema in New York and spent three days watching his own 29 movies.
LaBeouf began his career as a child actor in Disney Channel comedy Even Stevens, and went on to star in the Transformers movies.
He also starred alongside Harrison Ford in 2008's Indiana Jones and the Kingdom of the Crystal Skull.
- Bang! Showbiz
