The Lanckoroński Gallery exhibits collections of European painting, sculpture and decorative arts, as well as valuable specimens of historical weaponry. In total, there are more than 600 exhibits.

The most important part of the Lanckoroński Gallery consists of 37 objects donated to the Royal Castle in Warsaw in 1994 by Professor Karolina Lanckorońska. She was the last heiress of an aristocratic family which, over the course of two centuries, amassed one of the largest private collections of works of art in Europe in its Viennese palace. Of particular importance within this collection are 15 works that were the property of King Stanislaus Augustus in the 18th century, sold by his heirs after the monarch's death.

The undisputed pearls of this collection are two portraits by Rembrandt van Rijn, one of the greatest painters in the history of European art, these are: Girl in a Picture Frame and Scientist at a Desk. They are among some of the most valuable paintings permanently in Poland.

Other paintings exhibited in the Masterpiece Gallery also deserve mention: Adam and Eve from the workshop of Lucas Cranach St., The Smoker and the Drunkard by Adriaen van Ostade, Saint Mary Magdalene by Peter van Lindt, The Sea Storm by Ludolf Backhuysen or Still Life with Violin, Paintings and Self-portrait by Cornelius Norbertus Gysbrechts.