The current form became popular in the North America in the 19th century Promoter - Thomas Nast. Used to be green initially. Some people associate it with coca cola campaigns.

Santa Claus in his modern red-suited form became popular in North America during the 19th century, largely due to cartoonist Thomas Nast's illustrations. Earlier depictions showed him in green robes, like the Ghost of Christmas Present in Dickens' A Christmas Carol. While Coca-Cola's 1930s advertising campaigns helped popularize the modern image, they did not invent it - Nast's drawings came first and established the visual foundation.