She acted as the regent of the County of Holland during the minority of her nephew Count Floris V between 1256 and 1263.

On 9 October 1246, Adelaide married John I of Avesnes, Count of Hainaut.

Her religious interest is reflected in that three of her sons became bishops,[2] and her one daughter became an abbess.

She gave Town privileges to Schiedam, which afterward had the right to be called a city.

She ordered the construction of the Schielands Hoge Zeedijk, which today continues to protect 3 million inhabitants in a wide area around Rotterdam.