Ambroży Mieroszewski was a Polish painter who was Frédéric Chopin's first known portraitist.

Mieroszewski was active in Warsaw, in the Kingdom of Poland, at least as early as 1829.

Mieroszewski's works included oil portraits, painted in 1829, of composer Frédéric Chopin (the earliest known portrait of him); his parents — Nicolas Chopin (1771–1844) and Justyna Chopin, née Krzyżanowska (1782–1861); the older sister of Fryderyk (as he then was) Ludwika (1807–1855), and his younger sister Izabela (1811–1881). In that same year, Mieroszewski also painted a portrait of the Fryderyk's first professional piano teacher, Wojciech Żywny.

All six portraits were the property of Laura Ciechomska of Warsaw when they were lost in the opening days of World War II, in September 1939. Only black-and-white photographs of them survive, though attempts have been made to reconstruct the paintings in color—the portrait of Fryderyk (Frédéric), in 1968 by Anna Chamiec; the other Chopin family members, in 1969 by Jan Zamoyski; and Wojciech Żywny, in 1969 by Jadwiga Kunicka-Bogacka.