Tvrdonice (German: Turnitz) is a municipality and village in Břeclav District in the South Moravian Region of the Czech Republic.

It lies in a flat landscape of the Lower Morava Valley.

In 1538, the village was promoted to a market town, but it later lost the title.

The only protected cultural monuments in Tvrdonice are a statue of Saint John of Nepomuk from the end of the 19th century and a Baroque calvary, which dates from 1760.

The new neo-Gothic church was built in 1881–1884, but it has to be demolished in 1939 due to cracks caused by the hillside location.