Subjects for her paintings include actresses Lillian Russell and Marie Tempest; wealthy socialites Caroline Schermerhorn Astor, Emily Havemeyer (the wife of Theodore Havemeyer); members of Britain's royal family and London society such as King Edward VII, Alice Keppel, and Consuelo Vanderbilt, the Duchess of Marlborough; as well as members of the Russian royal family, including Czar Nicholas II and his wife, Czarina Alexandra Feodorovna; and wealthy industrialists such as Cecil Rhodes.

On July 4, 1900, Küssner married Captain duPont Coudert in a private ceremony attended only by their mothers in the sacristy at St. Patrick's Cathedral in New York City.

[6] During the early years of her career in Terre Haute, Indiana, Küssner painted miniature portraits of the likenesses of wealthy local residents that included members of the Fairbanks, Minshall, Baker, and Reynolds families.

Armed with introductions from her school friend and state actress Alice Fischer, as well as examples of her work, Küssner began to receive commissions to painted portraits of Manhattan's elite.

Through Paget's social connections, Küssner received commissions to paint miniature portraits of British royalty and London society that included Consuelo Vanderbilt, the Duchess of Marlborough.

In 1899, Küssner traveled to St. Petersburg, Russia, to paint miniature portraits of several members of the Russian royal family, including Czar Nicholas II and his wife, Czarina Alexandra Feodorovna at the Winter Palace.

[10] In 1899 Küssner traveled to southern Africa to obtain permission from Cecil Rhodes, a British diamond mining magnate, to paint his miniature portrait.

[19] A New York Times article in 1901 claimed that Amalia Küssner Coudert was "meeting with great success" in London,[14] but, for the most part, her career dwindled and eventually ended after her marriage.

[10] Küssner duPont Coudert's most notable work after 1900 included a return trip to Russia in 1902 to paint a second miniature portrait of Czarina Alexandra Feodorovna.

[20][21] Although Amalia and Charles duPont Coudert maintained a mansion in New York, which was a wedding gift from his mother, the couple spent most of their married life traveling d throughout Europe.

In 1911, the dePont Couderts loaned a Pierre Puvis de Chavannes painting titled "Child Gathering Apples" to the Metropolitan Museum of Art.