Matt plays Prince Phillip while Claire takes on the role of Queen Elizabeth in The Crown
Claire oozed glamour in a sheer black Valentino gown, which she described as "so beautiful" and said there was "nothing else she wanted to wear" to the awards.
The floor-length number was layered over a plunging pink slip and featured a pretty embroidered floral pattern throughout.
The stunning dress was cinched in at her waist with a black ribbon belt and included an embellished collar.
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The pair cosied up to one another as they were reunited at the awards
Matt Smith looked dapper in a black tuxedo
Her blonde locks were styled in a chic up 'do while she she sported lashings of mascara and a slick of pink lipstick to compliment her radiant complexion.
Meanwhile, Matt looked dapper in a black tuxedo which he paired with suede black slip-on shoes.
The pair arrived at the event together and were more than happy to pose for photographs together in the red carpet.
Speaking to People magazine, the duo opened up about their royal experiences, with Claire revealing she has only visited Buckingham Palace once despite playing the monarch for The Crown.
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Eva Longoria, Emilia Clarke and Helen Mirren top the best dresses list at the Screen Actors Guild Awards 2016
Claire Foy stole the spotlight in a flowing Valentino gown
"I met the Queen and Prince Phillip," she explained. "She touched my hand and I touched hers. It was on Valentine's Day too."
The actress is nominated for Outstanding Performance by a Female Actor in a Drama Series for her role as Queen Elizabeth.
The cast of the Netflix show were also nominated for Outstanding Performance by an Ensemble in a Drama Series.
The Crown is available to stream now on Netflix.