[1] He is credited with a mostly peaceful reign, modernizing administration, policies beneficial to trade, generally acting in the interests of his peasants at the expense of nobility, and reclaiming land from the sea.

His dramatic murder, said by some to have been arranged by King Edward I of England and Guy, Count of Flanders, made him a hero in Holland.

In 1274 he faced an uprising by nobles led by the powerful lords Gijsbrecht IV of Amstel, Zweder of Abcoude, Arnoud of Amstel, and Herman VI van Woerden, who held lands on the border with the adjacent bishopric of Utrecht (the area of Amsterdam, Abcoude, IJsselstein, and Woerden) at the expense of the bishop.

In 1282 Floris again attacked the troublesome Frisians in the north, defeating them at the battle of Vronen, and succeeded in retrieving the body of his father.

In the meantime he had received Zeeland-bewester-Schelde (the area that controls access to the Scheldt river) as a loan from the Holy Roman King Rudolf I of Germany in 1287, but the local nobility sided with the count of Flanders who invaded in 1290.

Floris arranged a meeting with count Guy of Flanders, but he was taken prisoner in Biervliet and was forced to abandon his claims and then set free.

Edward I subsequently prohibited all English trade with Holland and conspired with Guy of Flanders to have Floris kidnapped and taken to France.

The humiliated lords Gijsbrecht IV of Amstel and Herman of Woerden, together with Gerard van Velsen, captured Floris during a hunting party and brought him to Muiderslot castle.

The news of the capture spread quickly; afraid of the people, four days later the lords together with their captive left the castle to get to a safer place.