Originally bought by Fox as a vehicle for Betty Grable, however, after the success of Niagara (1953) (which featured Marilyn Monroe), however the studio believed they had a more potent and far less expensive sex symbol than Grable (who was earning around $150,000 per picture vs. Monroe's $18,000). Monroe kept insisting on retakes despite approval of takes by the director. When Fox asked director Howard Hawks how production could be sped up he retorted: "three wonderful ideas: Replace Marilyn, rewrite the script and make it shorter, and get a new director."

Monroe wears a gold lame evening dress previously worn by Ginger Rogers in Dreamboat (1952).

In the "Ain't There Anyone Here For Love" sequence, Jane Russell's fall into the pool was an accident. When Hawks saw the dailies, he kept it in the film.

At least one other number was shot, then cut. In the original theatrical trailer, Jane and Marilyn were shown among dancers, climbing the steps of a slide in a children's playground. The song was probably "Sunshine, Sunshine" from the Broadway score, which celebrated a bright day in a park. Marilyn and Jane wear the costumes when Tommy Noonan corners them backstage in the French nightclub.

A song written for Marilyn to sing in this picture, "Down Boy," was rejected, but later sung by Betty Grable in "Three For the Show."

The famous "Diamonds are a Girl's Best Friend" musical number was lip synched by Monroe. Her performance of the song was actually digitally put together in the studio.

Madonna's video "Material Girl" was inspired by Marilyn Monroe's dance number, "Diamonds are a Girl's Best Friend."

In 1954, The Writer's Guild of America nominated "Gentlemen Prefer Blondes," written by Charles Lederer based on a story by Anita Loos, for a "Best Written American Musical" award. The award was given to the film "Lili," which starred Leslie Caron. "Lili" was written by Helen Deutsch based on a story by Paul Gallico.

Tagline for Gentlmen Prefer Blondes:
"The Two M-M-Marvels Of Our Age In The Wonder Musical Of The World! "

Due to the success of the film "Gentlemen Prefer Blondes," Jane Russell and Marilyn Monroe were invited to be immortalized by imprinting their hand prints, feet and signatures in the sidewalk in front of Graumann's Chinese Theater for their 104th ceremony. Prior to their ceremony, Marilyn suggested that Jane should lean over in the cement while she, Marilyn, ought to sit down in it to "leave prints that better reflect our personalities." Marilyn dotted the "I" in her name with a rhinestone in reference to her hit song, "Diamonds Are a Girls' Best Friend," from the film Gentlemen Prefer Blondes. It was reported that two days later, once the cement had dried, Marilyn walked to the theatre from her nearby apartment at two a.m. to stand in her own footprints. See Marilyn's signature here.