Stenbockska Palatset, Baroque castle in Riddarholmen, Stockholm, Sweden.

Stenbockska Palatset is a Baroque castle on Riddarholmen featuring a symmetrical stone facade and large rectangular windows distributed across three stories. The building displays typical early Baroque characteristics with ornately designed portals and detailed exterior decorations.

The plot, known as Hörningsholmstomten, belonged to the Sture family in the 16th century and passed by inheritance to the Stenbocks. Fredrik Stenbock built a palace here in the 1640s; its core was rebuilt between 1661 and 1671 for his son Johan Gabriel Stenbock under architect Nicodemus Tessin the Elder. Carl Hårleman led interior work in the 1730s–40s, and the National Archives occupied the building from 1865 to 1968.

The palace takes its name from the Stenbock family, who inherited the Hörningsholm plot on which it stands. From 1865 to 1968 it housed the National Archives, and since 2009 parts of the Svea Court of Appeal have used it. Rococo door overdoors by Johan Pasch, made in the 1730s and 1740s, have been brought out and can be seen in the building.

The building is easily visible from outside as it sits prominently on Birger Jarls Square in a well-positioned location on Riddarholmen. Visitors should note that the palace now functions as a courthouse, so interior access may be limited depending on official activities.

On 17 March 1735 the palace hosted Sweden's first Masonic reception: Count Axel Wrede Sparre accepted Carl Gustaf Tessin as the first member of his lodge. The building later housed the Seraphim Order's offices until 1864.