De Lier lies about 5 km north of Maassluis, and is about 6 feet (1.8 m) below sea level.

The village got its name from the name of an old river called Lee (De Lier) [nl].

On 26 March 1963, it was granted its own coat of arms, and on 14 April 1965, it adopted the flag it has today.

On 1 January 2004, it merged with Naaldwijk, 's-Gravenzande, Monster, and Wateringen to form the municipality of Westland.

[1] The statistical area "De Lier", which can also include the peripheral parts of the village as well as the surrounding countryside, has a population of around 11,470.