According to Elogius Kiburger, the author of the Strättliger Chronicle, in 933 the King of Burgundy, Rudolph II, built the Castle.
Shortly thereafter, the Freiherr von Strättligen settled in the castle. Portions of the current castle shield walls and main tower were built during the 12th century and by the 13th century the town of Spiez existed outside the castle walls.
By 1280, the castle was listed as an Imperial fief under Vogt Richard de Corbières.
In 1289, the Freiherr von Strättligen was co-owner of the castle along with a succession of other noble families.
In 1308, King Albert I of Habsburg was murdered at Windisch on the Reuss, by his nephew Duke John Parricida.
As part of their retaliation for the murder, the Habsburgs withdrew half of the Spiez fief from Thüring von Brandis and granted the whole fief to Johannes von Strättligen. Thirty years later, in 1338, Johannes sold the castle, town, church and surrounding villages to Johann II von Bubenberg who was the Schultheiss of Bern.
By 1340, the Bubenberg-appointed vogt took orders from Bern, but was obligated to raise troops for the Habsburgs. As Bern was de facto independent from their former overlords, the Habsburgs, this created an unstable situation which remained for over 40 years.
After the Bernese and Swiss Confederation victory over the Habsburgs in the Battle of Sempach in 1386, the Habsburgs gave up their land claims west of the Aare, which included Spiez.
The castle and surrounding land remained with the Bubenberg family until their extinction in 1506, when it was acquired by Ludwig von Diesbach. Von Diesbach held it for ten years before Ludwig von Erlach acquired the castle and lands.
The old castle was expanded in several stages during the Late Middle Ages but little is known about the specific dates or what was changed. In 1600, the great hall and the northern buildings were expanded and renovated.
During the 17th and 18th centuries the south "New Castle" was built and then expanded and redecorated in the late Baroque style. The castle was surrounded with gardens, vineyards and forests.
The von Erlach family ruled the town and villages until the 1798 French invasion.
After the invasion and the creation of the Helvetic Republic, the von Erlach family lost their land rights and jurisdiction over the village, but retained ownership of the castle until 1875.
After 1875, the castle passed through several owners until a foundation bought the castle and associated church. The gardens are now open to the public and the castle rooms are used for conferences, concerts, exhibitions and other events.