Beautiful in a burgundy halter neck dress, Charlene was the image of Hollywood glamour – a look Albert's mother would no doubt have been proud of.
The blonde royal was seen looking closely at the pictures and outfits on display as the pair toured the exhibition at James Mitchner Library in Doylestown, Pennsylvania.
Prince Albert was thrilled to open the collection – for which he filmed a video tribute to the Hollywood princess-turned real life royal.
"I'm deeply touched by your interest in my mother and her rich legacy,' he says in the video, which will be shown to the public attending the retrospective.
"Most of the world knows my mother first as a Hollywood film actress, then as the princess of Monaco.
"She was indeed a beautiful and talented woman and a fashion icon but that is just the surface of her life."
The principality leader speaks of his mother's lifetime passions, saying: "She left a successful Hollywood acting career to pursue her heart. During her lifetime, she became a United Nations advocate for children and an international spokesperson for arts and culture."
"She also established an enduring legacy as president of the Monaco Red Cross and through the Princess Grace Foundation, which is dedicated to identifying and assisting emerging talents in theatre, dance and film by awarding grants in the form of scholarships, apprenticeships and fellowships."
He continues: "Those of us who were fortunate enough to know my mother, her family and friends, knew her to be a genuine, warm and loving woman. A woman who always put her family first.
"I hope that through experiencing this exhibition, you will be able to get a glimpse of the real Grace Kelly, the woman beyond the icon, my mother."
It was back in 1955 that the the Hollywood beauty met and fell in love with Prince Rainier, and the couple married the following year, signalling the end of her career.
Beloved by the people of Monaco, the princess consort was tragically killed in a car accident in September 1982. She was survived by her husband until 2005, and the couple's three children.