Katharine McPhee glows in glittery off-the-shoulder jumpsuit at themed Mary

Mary, Queen Of Scots bows in theaters Christmas Day.

And Katharine McPhee posed up a storm at Vanity Fair and Focus Features’ Thursday night party celebrating the movie in Los Angeles.

The 34-year-old bombshell posed up a storm with a lady clad in elaborate period costume that perfectly evoked the movie’s 16th century setting.

Smashing: Katharine McPhee posed up a storm at Vanity Fair and Focus Features' Thursday night party celebrating the movie Mary, Queen Of Scots in Los Angeles

Smashing: Katharine McPhee posed up a storm at Vanity Fair and Focus Features’ Thursday night party celebrating the movie Mary, Queen Of Scots in Los Angeles

Katharine was a glamour queen in an off-the-shoulder black jumpsuit with glittering accents around the waistline and up over its one strap.

The actress and singer, whose music mogul fiance David Foster is more than twice her age, accentuated her screen siren features with makeup.

Mary, Queen Of Scots tells of the battle of wills between the title character (Saoirse Ronan) and her cousin Elizabeth I Of England (Margot Robbie).

The conflict between them eventually led to Mary’s conviction of an attempt to assassinate the English queen, and her consequent execution.

Glorious: The 34-year-old bombshell posed up a storm with a lady clad in elaborate period costume that perfectly evoked the movie's 16th century setting

Glorious: The 34-year-old bombshell posed up a storm with a lady clad in elaborate period costume that perfectly evoked the movie’s 16th century setting

This new movie is directed by the Donmar Warehouse’s artistic director Josie Rourke, with a script by House Of Cards creator Beau Willimon.

Queen Of Scots: The True Life Of Mary Stuart, a 2004 nonfiction book by Cambridge historian John Guy, served as the basis for the upcoming flick.

Both leading ladies have been nominated for Academy Awards – Margot once and Saoirse three times – though neither of them has won.

Looking sensational: Katharine was a glamour queen in an off-the-shoulder black jumpsuit with glittering accents around the waistline and up over its one strap

Looking sensational: Katharine was a glamour queen in an off-the-shoulder black jumpsuit with glittering accents around the waistline and up over its one strap

Saoirse got her first Oscar nod for Atonement, a movie she acted in when she was only 12, and then was nominated again for the 2016 drama Brooklyn. 

At this March’s Academy Awards, Saoirse and Margot were nominated against each other, the former for Lady Bird and the latter for I, Tonya.

Neither of them wound up snatching the prize from the other, however, as Frances McDormand won for Three Billboards Outside Ebbing, Missouri.