Carrie and Boris Johns’n son Wilfred also made an appearance as he was pictured playing on the beach with Mrs Johnson and Dr Biden. The two women were pictured dipping their feet in the sea.
Mrs Johnson wore a red mid-length dress, which appeared to be a £325 gown by London-based designer L.K.Bennett, for the walk.
Dr Biden wore a black and white polka-dot dress with a black blazer.
The First Lady’s blazer, which carried the word “love” on the back in studs, appeared to be by French brand Zadig and Voltaire.
After having tea with Mrs Johnson this afternoon, Dr Biden told reporters: “It’s really nice to be here in Cornwall. It’s my first time.
“Obviously it’s beautiful for those of you who have been here before.”
She said that she and her husband were looking forward to meeting the Queen as part of their visit.
Dr Biden added that the couple hoped to focus on education in their discussions with the royals.
She said: “We’ve looked forward to this for weeks and now it’s finally here. It’s a beautiful beginning.”
It came ahead of a potentially tricky meeting between the two leaders.
Mr Biden expected to use the meeting to warn Mr Johnson not to let the row over Northern Ireland’s Brexit arrangements put the Good Friday Agreement at risk.
Mr Johnson said he would not disagree with Joe Biden on his suggestion they both “married way above our stations” after the two couples went for a stroll outside Carbis Bay Hotel in Carbis Bay.
As the two men were sitting next to each other in the hotel, where the G7 summit will be hosted, Mr Biden said: “I told the Prime Minister we have something in common.
“We both married way above our stations.”
Mr Johnson responded: “I’m not going to dissent on that one.
“I’m not going to disagree with you there or indeed on anything else, I think highly likely.”
The two leaders and their wives admired the view near the luxury hotel, with Mr Biden saying: “It’s gorgeous.
“I don’t want to go home.”