| Official Name: | Bang Khun Si |
| Native Name: | แขวงบางขุนศรี |
| Settlement Type: | Khwaeng |
| Subdivision Type: | Country |
| Subdivision Type2: | Province |
| Subdivision Name2: | Bangkok |
| Subdivision Type3: | Khet |
| Subdivision Name3: | Bangkok Noi |
| Area Total Km2: | 4.360 |
| Area Footnotes: | [1] |
| Population As Of: | 2019 |
| Population Total: | 31,689 |
| Timezone: | ICT |
| Utc Offset: | +7 |
| Postal Code Type: | Postal code |
| Blank Name: | TIS 1099 |
Bang Khun Si (Thai: บางขุนศรี, in Thai pronounced as /bāːŋ kʰǔn sǐː/) is a khwaeng (subdistrict) of Bangkok Noi District, in Bangkok, Thailand. In 2019, it had a total population of 31,689 people.[2]
The name is derived from a canal that runs through the west area, Khlong Bang Khun Si, also known as Khlong Chak Phra.
Bang Khun Si covers the central-southwest area of Bangkok Noi, with a total area of 4.360 km2 (1.683 mi2), regarded as the largest subdistrict of Bangkok Noi.
The area is bordered by neighbouring subdistricts (from north clockwise): Bang Khun Non in its district (Southern Railway Line is borderline), Siri Rat and Ban Chang Lo in its district (Charan Sanit Wong Road is a borderline), Wat Tha Phra in Bangkok Yai District (Khlong Mon is a borderline), Khuha Sawan in Phasi Charoen District (Khlong Bang Chueak Nang is a borderline), Khlong Chak Phra in Taling Chan District (Khlong Chak Phra is a borderline), respectively.