Phon Ngam (Thai: โพนงาม) is a tambon (subdistrict) of Det Udom District, in Ubon Ratchathani Province, Thailand.

[3] Neighbouring subdistricts are (clockwise from the south) Klang, Mueang Det, Kut Prathai, and Kham Khrang.

The region was first settled in 1906 by a group of 30 households led by Butprom Santa (บุตรพรม สันตะ); the first village was named "Nong Yaow" (หนองยาว; Long Pond), after the title of the pond nearby, and was followed by the second and third waves of the settlement in the 1940s.

[1] The tambon was created in 1986 by separating the district's capital, Mueang Det, into two halves, the eastern of which was named Phon Ngam subdistrict.

[1] The tambon was located in the central region of the Det Udom district, which is the low river plain of the Lam Dom Yai river, and covered 36 kilometers squares.