Before 100 BCCelts lived in the area. Later theFranks came into this area as graves from the 7th century prove. The first written document is theLife of the firstbishop of Münster. It describes how bishopLudger walked from Budica, now Büttgen, through the forest of Hamrithi. The earliest known written mention of Kaarst refers to it as 'Karlesforst' and dates back to 1218. Karl was a very common name for frankish nobles including kingCharlemagne ('Karl der Große'), but a link between Charlemagne and Kaarst has not been proven.
Kaarst and Büttgen both have churches built in the 12th century. Both villages were destroyed byCharles the Bold duke ofBurgundy (Karl der Kühne, 1474–1475), in theCologne War (1585 to 1586) and in theThirty Years' War (1618–1648).Jan von Werth, a celebrated general during the Thirty Years' War, was born near Büttgen in 1591.
During the Thirty Years' War, Kaarst was attacked several times by hostile armies, e.g. the one of Northern-Hesse (Northern-Hesse collaborated withSweden andFrance, whereas the southern part ofHesse did not). Some time in 1642, a Hessian troop entered the city murdering the local preacher and destroying the vicarage. From 1794 till 1814 Kaarst was in the area occupied by France underNapoleon I. The French redrew district boundaries in 1798 and assigned Kaarst to Kanton Neuss. A relic of Napoleon I is the Nordkanal, a canal to connect the riversMaas andRhine.
In 1936 Büttgen had 4,400 inhabitants and Kaarst 2,000.
In 1975 Büttgen and villages around Kaarst were formally amalgamated into Kaarst to form administrative area with 33,500 inhabitants.
In the 2015 communal elections, Dr. Ulrike Nienhaus(CDU) was elected mayor of Kaarst with 55.8 percent of the valid votes. She was the first female mayor of Kaarst. In the 2020 communal elections, Ursula Baum(FDP) was elected mayor of Kaarst. She won the runoff election in September 2020 with 59.35 percent of the valid votes against Lars Christoph(CDU).[3]