The 46-year-old actor plays the role of superhero Vision in the Marvel Cinematic Universe and reprises his role in the third instalment of the 'Avengers' franchise.
Bettany took to Instagram to share the news.
"That's a wrap on me - 'The Vision'. I'll be seeing you all in May." wrote Bettany along with a behind-the-scenes video from the film's set.
"Avengers: Infinity War" will star Robert Downey Jr, Chris Evans, Mark Ruffalo, Scarlett Johansson, Chris Hemsworth, Anthony Mackie, Paul Bettany, Elizabeth Olson, Chadwick Boseman, Sebastian Stan, Don Cheadle, Chris Pratt, Dave Bautista, Zoe Saldana, Pom Klementieff, Benedict Cumberbatch, Benedict Wong, Sean Gunn, Tom Holland and Paul Rudd.
Director duo Anthony and Joe Russo, who helmed "Captain America: The Winter Soldier" and "Captain America: Civil War", are directing "Infinity War" as well as the fourth untitled "Avengers" film, which are being filmed back-to-back in Atlanta, Georgia.