Rock Band 4 represented Harmonix's return to the franchise after an almost three-year hiatus, following the diminishing popularity of the rhythm game market that started in 2009.

Announced on March 5, 2015, Rock Band 4 refocuses on the core gameplay of the franchise, reducing the emphasis on musical instruction that was employed by its predecessor, Rock Band 3, while emphasizing the game's social interactions, as well as new features enabling players to incorporate improvisation into their performance—such as "freestyle solos" on guitar, and "freeform melodies" on multi-part vocals.

Once sufficiently filled, the player is able to trigger "Overdrive" through various means depending on instrument, which doubles their scoring multiplier as well as boosting the band's overall performance meter.

To aid in the cooperative nature of the game, any scoring multipliers and remaining Overdrive are carried over between songs in Gig lists as well as between sets in the Career mode.

[10] Further, the audio feedback from these solos has been refined as to make whatever the player performs stay consistent and in-tune with the other active and backing instruments.

[4] Higher difficulty settings for vocals allow for "freeform melodies" where as long as the vocalist is in tune, they can improvise to a degree to add their personal touch to a song.

[14] In December 2016, Harmonix delayed the online addition until January 25, 2017 to make sure this feature covered all edge cases that they had encountered in testing.

[20] Harmonix released a patch to include online play on January 25, 2017, an oft-requested feature since Rock Band 4's launch; this will require players to have purchased the Rivals expansion (described below).

[14][15][21][22] Updates have included additional clothing and instruments for the in-game characters, including Vault suits as part of a promotional tie-in in Bethesda's Fallout 4, the goggle headgear worn by the protagonist Raz from Double Fine Productions' Psychonauts, outfits for characters from Gearbox Software's Battleborn, and instruments and outfits inspired by Mass Effect: Andromeda.

[22] The December 2016 update to Rivals provided twelve free songs to all owners from local Boston bands that were part of the interviews for the Rockumentary game mode.

[39] Harmonix's Greg LoPiccolo added that they did not want to try to introduce Rock Band 4 during the new consoles' first year where they would have to compete with major franchises.

[40] Funding for development was aided by $15 million in investments from Spark Capital and Foundry Group, not only to support Rock Band 4 but the remake of Harmonix' Amplitude and future projects involving virtual reality.

[42] Rigopulos stated that Ubisoft's competing Rocksmith series "is serving the audience that wants actual guitar instrumental instruction very well.

[48][49] The sudden release, along with a survey posted by Harmonix a few days later, indicated the possibility that the studio was planning to develop a new Rock Band game for eighth generation consoles.

[51] Rock Band 4 is expected to be the only retail release of the franchise for the current generation of consoles;[42] Rigopulos called the multiple-release cycle "taxing" on both the studio and consumers, and instead sees the game as a platform which they can continuously improve over the life of the title without excessive work.

[52] In March 2016, Harmonix launched a crowd funding campaign through the Fig platform to produce Rock Band 4 for personal computers, to have been released in the last quarter of 2016.

The game would have been released via Steam, allowing users to use the Steam Workshop to create their own songs and distribute it to others, with curation by Harmonix to avoid copyright infringements, in a manner comparable to the Rock Band Network but at a lower cost; they have already ported the previous Rock Band Network tools to offer to backers of the campaign.

Harmonix planned to allow compatibility with all existing instrument controllers from the various PlayStation 2, 3 and 4, and Xbox 360 and One platforms, and had begun working through details with Sony and Microsoft.

[53] The funding campaign failed to reach its goal, only obtaining about $793,000 of the $1.5M target; Harmonix has not ruled out approaching a personal computer version in the future as they are aware there is some demand for Rock Band there.

[62] At PAX East, a special Penny Arcade-themed guitar with artwork of Gabe was made available as a limited edition exclusive.

[64][66] The Adapter was developed by Mad Catz by experimenting with all legacy Xbox 360 controllers they wanted to support and verifying what inputs they sent via wireless connection.

Harmonix was also working to get backward compatibility for the Stage Kit, an add-on hardware unit for Xbox 360 owners that allowed for a smoke machine and light show display in time with the song.

A new guitar controller based on the Fender Jaguar features improvements to the strum bar and tilt sensor, while its neck can fold down for easier storage.

While part of this reduction in cost is attributed to the age of the game, Sussman stated that several factors relating to PDP's manufacturing and business models allows them to offer the packages at a more competitive price point.

However, following its initial shipment in November 2016, PDP affirmed that their terms of licensing with Harmonix only allowed them to produce a limited number of the units, less than the demand that was found for the device.

[79][81] IGN praised Rock Band 4 for remaining "every bit the magical cooperative gaming experience the series has always been", with a particular focus on its continuity in gameplay with previous installments, and its "party-friendly" improvements to managing multiplayer play.

However, it was acknowledged that the game's backward compatibility with songs purchased for previous versions provided a "massive incentive" for players with pre-existing libraries.

[89] GameSpot noted that the Freestyle Solos "genuinely enhance[d] the core experience", explaining that players "can actually create some really cool sounding stuff.

Regressions were also noted, such as a lack of practice modes beyond Freestyle Solo tutorials, the shallowness of character customization, and the removal of online multiplayer.

[98] Harmonix affirmed there were issues with more than 400 existing songs due to difficulties with licensing between them and Sony Computer Entertainment Europe but that they expect to have these available by early December 2015.