His work includes the scores of the television series Battlestar Galactica (2004), Agents of S.H.I.E.L.D., Black Sails, Outlander, The Walking Dead, The Lord of the Rings: The Rings of Power, The Serpent Queen, Percy Jackson and the Olympians, Halo, the video games Call of Duty: Vanguard, God of War and God of War Ragnarök, and the film Godzilla: King of the Monsters.

In 2003, McCreary worked under primary composer Richard Gibbs on the three-hour miniseries which served as a pilot for the reimagined series of Battlestar Galactica.

To date, six Battlestar Galactica soundtrack albums have been released, and have garnered a great deal of critical acclaim[9][10] and commercial success.

The score to the finale of season one, "Christopher Chance", used the largest orchestra ever assembled for episodic television, and he took the opportunity to rerecord the main title theme with a new orchestration with this larger ensemble.

[12] In a post on his blog on July 25, 2010, McCreary announced the new creative leadership brought in for season two had not asked him to return for it, and he would be leaving the series.

[citation needed] During Comic-Con 2010, Bear McCreary attended panels for AMC's The Walking Dead and NBC's The Cape to announce he would be composing the score for both television series.

[17] McCreary served as orchestral producer for the rock opera Metalocalypse: The Doomstar Requiem airing on Adult Swim on October 27, 2013.

[23] McCreary worked on several films providing additional music and conducting for My Baby's Daddy and Johnson Family Vacation before striking off on his own and scoring Rest Stop and Wrong Turn 2: Dead End, both direct to video.

McCreary's latest feature scores include Ava, The Babysitter: Killer Queen, Freaky and Paws of Fury: The Legend of Hank.

In June 2023, McCreary replacing[clarification needed] Thomas Newman as a score composer in the latest upcoming film The Last Voyage of the Demeter, directed by André Øvredal.

[26] McCreary also performed with his orchestra live at Sony's E3 2016 press conference throughout the show and composed the score of the 2018 God of War game.

[27] He also composed the music for its 2022 sequel, God of War Ragnarök, for which he also plays a minor character in the game, a Dwarf named Ræb.

Co-written and co-produced by McCreary’s brother, Brendan McCreary, who also contributes lead vocals to eight songs, the album features performances by Rufus Wainwright, Slash, Serj Tankian, Corey Taylor, Jens Kidman, Joe Satriani, Buck Dharma, Asdru Sierra, Griogair, Kim Thayil, Scott Ian, Brendon Small, Billy Boyd, Eivør, Guthrie Govan and Bryan Beller, Mike Keneally, Ben Weinman, Steve Bartek and John Avila, Warren Fitzgerald, Esjay Jones, Sigurjón Kjartansson, Raya Yarbrough, Mega Ran, and Gene Hoglan, along with spoken-word contributions from the companion graphic novel (published by Image Comics and Black Market Narrative) by actors Lee Pace, Danai Gurira, and Ryan Hurst.

[33] McCreary credits composers Jerry Goldsmith, Elmer Bernstein, Danny Elfman, Ennio Morricone, John Williams, Basil Poledouris, and Shirley Walker as being key to his growing up adoring film music.