Topoľnica (Hungarian: Tósnyárasd) is a village and municipality in Galanta District of the Trnava Region of south-west Slovakia.

The municipality lies at an elevation of 119 metres and covers an area of 10.475 km².

In the 9th century, the territory of Topoľnica became part of the Kingdom of Hungary.

After the Austro-Hungarian army disintegrated in November 1918, Czechoslovak troops occupied the area, later acknowledged internationally by the Treaty of Trianon.

Between 1938 and 1945 Topoľnica once more became part of Miklós Horthy's Hungary through the First Vienna Award.