| Conventional Long Name: | Nyland and Tavastehus County |
| Native Name: | Nylands och Tavastehus län Uudenmaan ja Hämeen lääni |
| Common Name: | Nyland |
| Subdivision: | County |
| Nation: | the Swedish Empire 1634-1809 Province of Grand Duchy of Finland 1809-1831 |
| Year Start: | 1634 |
| Event Start: | Established |
| Year End: | 1831 |
| S1: | Uusimaa Province |
| Flag S1: | Flag of Russia.svg |
| S2: | Häme Province |
| Flag S2: | Flag of Russia.svg |
| Capital: | Tavastehus |
| Title Leader: | Governor |
| Footnotes: | 1 |
Nyland and Tavastehus County was a county of the Swedish Empire in Finland from 1634 to 1809.
In 1775 whole northern part of the county (later Central Finland region) was transferred to the new Vasa County. Also a part of historical Satakunta was added to the Nyland and Tavastehus County from the Åbo and Björneborg County, while Upper Hollola was transferred to the new Kymmenegård County.
By the Treaty of Fredrikshamn in 1809 Sweden ceded all its territories in Finland, east of the Torne River, to Russia. The county still continued to exist as a province of the new autonomic Grand Duchy of Finland until 1831, when it was split to Häme Province and Uusimaa Province.