Not until the 19th Century was it divided into (upper) Oberschleissheim and (lower) Unterschleissheim for population and political reasons.

The first surviving document in which Schleißheim is mentioned comes from the year 785 AD in which Rihpalt von Slivesheim donated his estate to the diocese of Freising.

From 1856 to 1858 the first railway line from Munich to Landshut passed through Unterschleissheim, with a station in the nearby village of Lohhof.

Painters and illustrators such as Otto Hupp, Frank Behrens, Max Hein-Neufeld and Heinz Katzenberger should be mentioned.

During the Nazi Era, a forced labor facility was built in Lohhof to grow and process flax for the textile industry.

The “Valentinspark”, covering roughly 30 acres (120,000 m2) which was made possible at the instigation of former mayor Rolf Zeitler and opened on July 22nd, 2000, was rededicated on January 12th, 2024 as “Rudolf-Zeitler-Park”, in memory of him and his achievements.

Two S-Bahn stations on the Munich–Regensburg line, served by S1 trains, connect Unterschleißheim with the regional rail system.

A bridge crosses over the S-Bahn line in the middle of Unterschleißheim, called the Le Cres Brücke (named in honor of their sister city in France).