In exchange, the Avalanche acquired forward Mikhail Maltsev and a second-round selection this year from New Jersey.
By trading Graves, along with Avalanche defenseman Erik Johnson agreeing to waive his no-movement clause, the team can protect defensemen Devon Toews, Cale Makar and Samuel Girard. The Devils have plenty of room to protect Graves.
Protected lists are due Saturday, and the expansion draft is Wednesday.
The 26-year-old Graves had two goals and 13 assists over 54 games with the Avalanche last season. He led the team in blocked shots with 91 and was second in hits with 77.
He was dependable on the blue line for Colorado since he was acquired Feb. 26, 2018, from the New York Rangers. His plus-40 rating in 2019-20 led the league, the first time an Avalanche player accomplished the feat since Milan Hejduk and Peter Forsberg (plus-52) in 2002-03.
Graves will bolster a Devils defence that was so-so last season. The main cogs are Ty Smith, Damon Severson and P.K. Subban. Will Butcher spent much of the year in the doghouse.
"Ryan brings physicality, size, an ability to defend in tough situations and a fearless compete level that makes him tough to play against," Devils general manager Tom Fitzgerald said in a statement. "His assertive style of play and ability to play with young defensemen are characteristics that fit into what we are building with our group."
Colorado picks up another scoring threat to join the likes of Nathan MacKinnon and Mikko Rantanen. The 23-year-old Maltsev had nine points and three assists in 33 contests during his rookie season. He appeared in his first NHL game on Jan. 31, 2021, at Buffalo.
The 6-foot-3, 198-pound Maltsev was a fourth-round pick of the Devils in 2016. He also played in Russia, where he had a goal and seven assists in 35 career Kontinental Hockey League games with SKA St. Petersburg.
Colorado has quite a few big players who are free agents, including captain Gabriel Landeskog and goaltender Philipp Grubauer. There's also forwards Brandon Saad, Matt Calvert, Pierre-Edouard Bellemare and Carl Soderberg, goaltender Devan Dubnyk and defenseman Patrik Nemeth.