Catherine, 31, attended the National Portrait Gallery on Friday where artist Paul Emsley's work was revealed to a private audience which included the Duke of Cambridge.
"I think, from what I can see this morning, she's delighted with it. I'm very happy about that," Emsley said of Catherine's reaction.
The award-winning artist was commissioned by the gallery to capture Catherine and worked with the Duchess during a series of photography sessions.
The larger-than-life sized head and shoulders painting shows Catherine's flowing brunette hair and soft features against a dark background.
"In discussions it became clear that what she wanted herself, and I was very happy with that, was that the portrait should convey her natural self as opposed to her official self," Emsley told reporters, as published by The Independent online.
"The fact she is a beautiful woman is for an artist difficult. In the end I think what I tried to do really was to convey something about her warmth and her smile."
Asked of any royal feedback he received during the unveiling, Emsley said Catherine, who has a history of art degree, commented on the portrait: "It's just amazing".
The work was praised by prolific royal portrait artist Richard Stone, who said Emsley is "brave" to have embarked on a work of such large scale.
"It's very challenging to do something larger than life, and he seems to have pulled it off very well," said Stone, whose first royal commission was to paint the Queen Mother, which he went on to do six times.