The album reached number 25 on the US Billboard 200 and was certified gold by the Recording Industry Association of America (RIAA), denoting shipments in excess of 500,000 copies.

This reissue includes three bonus tracks (both of the aforementioned 12″ versions, and also the rare extended mix of "Inner City Spillover") as well as extensive liner notes.

In May 2023, a deluxe edition was released, consisting of the original album and a bonus disk of remixes pressed in transparent vinyl, and a lenticular cover.

[2] For the promotion of KooKoo, Chrysalis Records planned to display large posters of the album cover in various stations of the London Underground.

In The Boston Phoenix, Ken Emerson gave the album a mixed review, writing that "Harry comes across on KooKoo as inaccessible, invulnerable, and creepy.

... [T]hough KooKoo lacks the playful energy and innocence of Parallel Lines (1978), Blondie’s best album, it’s far more accomplished and fully realized than either of the band’s subsequent LPs.

"[7] Rob Sheffield wrote in the Spin Alternative Record Guide (1995), "KooKoo is disappointingly diffuse, and it's easy to hear what went wrong: while Harry meekly imitates the suave funk of Chic's classic Real People, Rodgers reverts to his true roots in European art-rock.