Krathum Baen (Thai: กระทุ่มแบน, pronounced [krā.tʰûm bɛ̄ːn]) is a district (amphoe) in the northern part of Samut Sakhon province, central Thailand.

Krathum Baen was a part of Mueang Samut Sakhon district. It was created in 1900. In 1926 the government added Tambons Tha Mai, Bang Yang, Nong Kok Khai, and Om Noi of Sam Phran district, Nakhon Pathom province to the district.

Neighbouring districts are (from the north clockwise): Sam Phran of Nakhon Pathom province; Nong Khaem and Bang Bon of Bangkok; Mueang Samut Sakhon and Ban Phaeo of Samut Sakhon Province.

The important water resources are the Tha Chin river and Phasi Charoen canal.

The name Krathum Baen meaning 'flat burflower-tree'.

The district is divided into 10 subdistricts (tambons), which are further subdivided into 76 villages (mubans). There is a city (thesaban nakhon), Om Noi, and a town (thesaban mueang), Krathum Baen. The non-municipal area is administered by eight tambon administrative organizations (TAO).

1. Talat Krathum Baen ตลาดกระทุ่มแบน 2. Om Noi อ้อมน้อย 3. Tha Mai ท่าไม้ 4. Suan Luang สวนหลวง 5. Bang Yang บางยาง 6. Khlong Maduea คลองมะเดื่อ 7. Nong Nok Khai หนองนกไข่ 8. Don Kai Di ดอนไก่ดี 9. Khae Rai แคราย 10. Tha Sao ท่าเสา

Krathum Baen Hospital is a general hospital operated by the Ministry of Public Health.

• Wat Tha Mai