Kouyoumdjian or Kouyoumjian (, derived from Turkish "kuyumcu" [kuyum "jewel" + cu "agentive/profession suffix"], meaning "jeweller" or "goldsmith") is an Armenian surname. Notable people with the surname include:
Dikran Sarkis Kouyoumdjian (1895–1956), later known as Michael Arlen, short story writer and novelist Juan Kouyoumdjian, Argentine naval architect Ohannes Kouyoumdjian (1852–1933), Ottoman Armenian official Robert Kouyoumjian (1923–2011), American electrical engineer Zaven Kouyoumdjian (born 1970), Lebanese talk show host