Sieradz County () is a unit of territorial administration and local government (powiat) in Łódź Voivodeship, central Poland. It came into being on January 1, 1999, as a result of the Polish local government reforms passed in 1998. Its administrative seat and largest town is Sieradz, which lies west of the regional capital Łódź. The county contains three other towns: Złoczew, lying south-west of Sieradz, Warta, lying north-west of Sieradz, and Błaszki, west of Sieradz.
The county covers an area of . As of 2006 its total population is 121,013, out of which the population of Sieradz is 44,045, that of Złoczew is 3,403, that of Warta is 3,388, that of Błaszki is 2,179, and the rural population is 67,998.
| Gmina | Type | Area (km2) | Population (2006) | Seat |
| Sieradz | urban | 51.2 | 44,045 | |
| Gmina Błaszki | urban-rural | 201.6 | 15,090 | Błaszki |
| Gmina Warta | urban-rural | 252.9 | 13,074 | Warta |
| Gmina Sieradz | rural | 181.6 | 9,788 | Sieradz * |
| Gmina Złoczew | urban-rural | 118.0 | 7,398 | Złoczew |
| Gmina Brzeźnio | rural | 128.7 | 6,351 | Brzeźnio |
| Gmina Wróblew | rural | 113.2 | 6,244 | Wróblew |
| Gmina Goszczanów | rural | 123.3 | 5,814 | Goszczanów |
| Gmina Burzenin | rural | 119.0 | 5,665 | Burzenin |
| Gmina Brąszewice | rural | 106.3 | 4,485 | Brąszewice |
| Gmina Klonowa | rural | 95.4 | 3,059 | Klonowa |
| * seat not part of the gmina | ||||
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