The ensemble cast consists of Daniel Day-Lewis, Marion Cotillard, Penélope Cruz, Judi Dench, Fergie, Kate Hudson, Nicole Kidman, and Sophia Loren.

Nine was nominated for four Academy Awards: Best Supporting Actress (Penélope Cruz), Best Art Direction (John Myhre and Gordon Sim), Best Costume Design (Colleen Atwood), and Best Original Song ("Take It All").

Having turned fifty and developed writer's block, he conjures all the women in his life, both alive and deceased, for inspiration, including: Luisa (née Acari), his wife; Claudia Jenssen, his star actress; Carla Albanese, his mistress; Liliane "Lilli" La Fleur, his costume designer and confidant; Stephanie Necrophorus, an American fashion journalist from Vogue; Saraghina, a prostitute from his childhood; and his beloved Mamma ("Overture Delle Donne").

Guido remembers Saraghina, a prostitute he and his schoolmates paid to teach them the joy of life's sensual pleasures (the art of love and sex) by dancing for them on a beach when he was nine ("Be Italian") before he was caught by the priests and whipped.

Failing to pacify Luisa, Guido meets Stephanie in the hotel's bar, who confesses that she adores his movies' style rather than their substance ("Cinema Italiano").

Sometime later, Guido is making that very film, directing actors representing younger versions of himself and Luisa, living in a small apartment and deeply in love.

[5] On April 16, 2007, it was reported that producer Harvey Weinstein was considering Gwyneth Paltrow, Anne Hathaway, Jennifer Lopez, Nicole Kidman, Judi Dench, Catherine Zeta-Jones and Renée Zellweger for the six major female roles in Nine, and that Weinstein and director Rob Marshall were also considering George Clooney, Javier Bardem, Antonio Banderas and Johnny Depp for the role of Guido.

[6] On August 20, 2007, Variety announced that Javier Bardem, Marion Cotillard and Penélope Cruz were in talks to star in Nine in the roles of Guido, Luisa, and Carla, respectively.

On May 14, 2008, Variety reported that Daniel Day-Lewis was in talks to star as Guido Contini, the film's lead character,[11] after Javier Bardem dropped out due to exhaustion.

[13] Antonio Banderas, who had starred in the Broadway revival, said he was "disappointed" at not being cast, but that he thought the trailer to the film looked great and only wished the "best" for everyone involved.

According to music supervisor Matt Sullivan, "One day during shooting at London's Shepperton Studios, Rob and I got called into Daniel's dressing room, which was designed as a 1960s film director's office...He's smoking a cigarette, in full outfit and in character, and he's telling us how he would like to see this number that he's performing.

[26] The former featured two of the characters watching one of the film's trailers on the Internet on a YouTube-esque website, and there were subtle setting alterations performed for the latter, including movie posters on the walls of various public places.

[citation needed] In a 2018 interview with The New Yorker, Rob Marshall revealed that he believes the Weinstein Company failed to market the film properly as it was a trickier sell than Chicago and should have started in festivals and smaller venues.

The critical consensus is: "It has a game, great-looking cast, led by the always worthwhile Daniel Day-Lewis, but Rob Marshall's Nine is chaotic and curiously distant.

Sophisticated, sexy and stylishly decked out, Rob Marshall’s disciplined, tightly focused film impresses and amuses as it extravagantly renders the creative crisis of a middle-aged Italian director, circa 1965".

[35] Richard Corliss of TIME magazine wrote that "Only Cotillard, as Guido's long-suffering wife Luisa, is in command of her character whether she's singing, speaking or just staring darts at her philandering mate."

Corliss also praised Cotillard's rendition of "My Husband Makes Movies", calling it a "lovely scene" and "a moment of emotional truth at the heart of this expertly made but hollow enterprise.

"[36] For Ali Plumb of Empire magazine, "Though slightly marred by a clunky structure and a lack of truly catchy tunes, Nine's wall-to-wall first-rate performances from its stellar cast (especially Cotillard) add a touch of class.

"[38] Alistair Harkness of The Scotsman called Nine "the worst film of the year" for "its absolute awfulness, for its mind-numbing shallowness, for its smug and self-satisfied cast, and for its ability to wreck Daniel Day-Lewis's otherwise unblemished record.