Frederick the Great reportedly felt compassion for her mother, and entrusted Frederica Charlotte to the care of his own wife, Elisabeth Christine of Brunswick-Wolfenbüttel-Bevern, with the words: "There is only this poor child remaining to her, and she can find no asylum save with you; let the little one have the apartments lately occupied by my niece of Holland.

On 29 September 1791 at Charlottenburg Palace, she married Prince Frederick, Duke of York and Albany, the second son of the British King George III and Queen Charlotte.

[2] Frederica Charlotte had been chosen upon the wish of Frederick the Great, who allowed George III to read a letter from Frederica Charlotte displaying her gentle and affectionate nature, successfully anticipating that this would touch George III and make him inquire for her to marry his son.

[2] Frederica Charlotte and Frederick separated and the Duchess retired to Oatlands Park, Weybridge, where she lived eccentrically until her death.

"[3] In 1827 (after her death), she was called: "a harmless but an eccentric little woman, with an extraordinary fondness for cats and dogs, some indications of the German severity of family etiquette, which gave her household the air of Potsdam, and but a slight share of those attractions which might retain the regards of a husband—young, a soldier, and a prince.

Frederica kept many dogs and was apparently very devoted to monkeys[5] Her father-in-law once remarked : "Affection must rest on something, and where there are no children, animals are the object."