In October 2009, Robert Fripp collaborated with Steven Wilson to remix the original master recordings of In The Court of the Crimson King in a new stereo and 5.1 surround sound mix, released as the album’s 40th Anniversary edition. The album was sold as three different packages: a two-CD set with the old and new stereo versions, a CD and DVD set with the new stereo and surround sound mixes, and a six-disc (5 CD/1 DVD) box with all mixes and bonus audio and video tracks.

In 2019, the album was remixed in 5.1 and stereo by Steven Wilson once again for a 50th anniversary box set of the album. Wilson expressed satisfaction with his 2009 remix, but stated that his 50th anniversary mixes are a significant improvement, being more faithful to the original 1969 mix and benefitting from his 10 years of ensuing experience. The box set includes 3 CDs and a Blu-ray. The Blu-ray features the all-new 2019 stereo and 5.1 mixes encoded at 24/96 resolution, the 2004 “Original Master Edition” with the 1969 mix (also encoded at 24/96), a complete alternate version of the album comprising 2019 Steven Wilson mixes and 2019 instrumental mixes while the three CDs in the box set feature the new 2019 stereo mix, an expanded edition of the alternate album in the Blu-ray and the “Original Master Edition” plus additional tracks. A Dolby Atmos mix was released as part of King Crimson’s ‘The Complete 1969 Recordings’ in 2020.