Chris Carter pitched Millennium to Fox as 'Seven in Seattle,' reflecting the influence of the film Se7en on its dark, rain-soaked atmosphere and religiously inspired serial killer plot.

Carter said he was influenced by the Bible, Dostoyevsky and Mary Shelley while planning the series, and one of its working titles was simply '2000' before Millennium was chosen.

Fox gave Chris Carter a budget of nearly $1.5 million per episode following his success with The X-Files, and allowed him creative freedom to design the show's distinctive visual style.

Fox executives were initially unsure Lance Henriksen was right for the lead role and considered William Hurt instead, until they learned Hurt had no interest in acting for television.

Chris Carter had tried unsuccessfully to cast Henriksen on The X-Files several times; later, while both were in Vancouver, Carter slipped a personal note under Henriksen's hotel room door expressing his admiration and hope to work with him someday, and Carter subsequently wrote the Millennium pilot with only Henriksen in mind.

Henriksen initially turned down the Millennium pilot script after his manager told him it was for television, but he changed his mind after speaking directly with Chris Carter.

For season two, Glen Morgan and James Wong took over production from Chris Carter, who was focused on The X-Files' fifth season and its motion picture; they deliberately reduced the gore and added humor and a more varied episode structure similar to The X-Files' mix of monster, conspiracy and personal stories.

For season three, Chris Carter resumed control after Morgan and Wong departed, and he moved the show's setting from Seattle to Washington, D.C. in an effort to make the stories more accessible and return to the tone of season one.

The series' pilot episode drew 17.72 million viewers in the United States, but ratings declined significantly, with the season two premiere gathering only 7.75 million viewers.

Despite Fox being willing to renew Millennium for a fourth season, it was ultimately cancelled because Chris Carter chose to focus his efforts on his new series Harsh Realm.

Frank Black and his daughter Jordan made their final on-screen appearances in a seventh-season episode of The X-Files titled 'Millennium,' created as a form of closure for the cancelled series.

After cancellation, the FX cable network acquired the off-network syndication rights to Millennium for $20–25 million, and the horror channel Chiller later began airing the show nightly starting in 2008.

Following the DVD release of the series, Lance Henriksen proposed a continuation or film revival of Millennium, and later supported the 'Back to Frank Black' campaign advocating for the character's return; Chris Carter also expressed interest in such a film, though 20th Century Fox never publicly commented on the idea.