| Tiassalé Department | |
| Native Name: | Département de Tiassalé |
| Native Name Lang: | fr |
| Settlement Type: | Department |
| Subdivision Type: | Country |
| Subdivision Type1: | District |
| Subdivision Name1: | Lagunes |
| Subdivision Type2: | Region |
| Subdivision Name2: | Agnéby-Tiassa |
| Seat Type: | Departmental seat |
| Seat: | Tiassalé |
| Established Title: | 1988 |
| Established Date: | Established as a first-level subdivision via a division of Abidjan Dept |
| Established Title1: | 1997 |
| Established Date1: | Converted to a second-level subdivision |
| Established Title2: | 2011 |
| Established Date2: | Converted to a third-level subdivision |
| Established Title3: | 2012 |
| Established Date3: | Divided to create Taabo Dept |
| Government Footnotes: | [1] |
| Leader Title: | Prefect |
| Leader Name: | Jules Gouesse |
| Unit Pref: | Metric |
| Area Total Km2: | 2360 |
| Population Footnotes: | [2] |
| Population Total: | 278954 |
| Population As Of: | 2021 census |
| Population Density Km2: | auto |
| Timezone: | GMT |
| Utc Offset: | +0 |
Tiassalé Department is a department of Agnéby-Tiassa Region in Lagunes District, Ivory Coast. In 2021, its population was 278,954 and its seat is the settlement of Tiassalé. The sub-prefectures of the department are Gbolouville, Morokro, N'Douci, and Tiassalé.
Tiassalé Department was created in 1988 as a first-level subdivision via a split-off from Abidjan Department.[3]
In 1997, regions were introduced as new first-level subdivisions of Ivory Coast; as a result, all departments were converted into second-level subdivisions. Tiassalé Department was included in Lagunes Region.
In 2011, districts were introduced as new first-level subdivisions of Ivory Coast. At the same time, regions were reorganised and became second-level subdivisions and all departments were converted into third-level subdivisions. At this time, Tiassalé Department became part of Agnéby-Tiassa Region in Lagunes District.
In 2012, two sub-prefectures were split from Tiassalé Department to create Taabo Department.[4]