Delta previously charged fees for some of the entertainment, such as $6 for new release movies and $1 per episode of HBO shows.
"Delta Studio offers up to 300 movies, 750 TV shows, 100 foreign film titles, 2,400 songs, 18 channels of live satellite TV on select aircraft and a selection of games on aircraft with seat-back entertainment systems," the airline said in a news release.
The airline said its entertainment offerings will continue to include "recent box office hits" like "Hail, Caesar" and "Batman v Superman: Dawn of Justice."
Delta said the move to make in-flight entertainment free is part of its "investments in the customer experience."
Entertainment options will vary by the route and type of aircraft.