The Denmark frontman, who spent last season on loan at Sunderland, was confirmed as a Juve player in the last hour of Italy's transfer window, which shuts at 6pm BST.
"I can now finally say I am a Juventus player," tweeted Bendtner. "Very proud and can't wait to wear the stripes! I hope we will have great times together.
"I want to fulfill my potential here and show the fans my absolute best as that is yet to come. I am sure I will ;)"
The Turin club are believed to have agreed a deal with Arsenal that could see the 24-year-old permanently move to the Old Lady for around £5m at the end of the season.