Mueang Chachoengsao (Thai: เมืองฉะเชิงเทรา, pronounced [mɯ̄a̯ŋ t͡ɕʰàʔ.t͡ɕʰɤ̄ːŋ.sāw]), formerly named the Mueang Paet Rio District (Thai: เมืองแปดริ้ว),[citation needed] is the capital district (amphoe mueang) of Chachoengsao province, Eastern Thailand.

The present district office is close to the bank of the Bang Pakong River in Na Mueang subdistrict.

Neighboring districts are (from the north clockwise): Bang Nam Priao, Khlong Khuean, Bang Khla, Ban Pho of Chachoengsao Province; Bang Bo of Samut Prakan province; Lat Krabang and Nong Chok of Bangkok.

The important water resource are the Bang Pakong River and Khlong Nakhon Nueang Khet.

Mueang Chachoengsao is divided into 19 subdistricts (tambons), which are further subdivided into 192 administrative villages (mubans).