It is believed that the castle was built around year 1000 by the Patriarchate of Aquileia and managed by their local vassal knights named de Treuen.
Records attest that the castle's first vassal was Konrad de Treuen, who was then followed by Bernard, Henrik and Ulrik de Treuen between the years 1243 and 1245.
A record from 1349 mentions the knight Hajncel, and Aquileian charters from 1358 refer to the knight Johannis de Treuen as the castle's overseers.

First mentions of the castle however date back to 1386 and 1436, and refer to it as Turn ze Treuen and turn zu Trefen mit dem purkchstal vnd dem pawhof, respectively.

According to a historian Valvasor, after the decline of knights of Treuen, the castle's ownership first passed to Counts of Ortenburg, and then to Counts of Celje, who owned the castle until 1456.
With the demise of Counts of Celje, the castle was handed over to the Habsburgs as part of an inheritance agreement.

In the Early modern period the castle changed several hands.
Written recordings list the following owners:
1601: Gabrijel Križanič;
1652: Jurij Jankovič;
1679: Wolf Konrad Jankovič;
1685: Matej Kowatschitsch pl.
Schmiedhofen, who was a toll collector of provincial tollhouses in Jesenice and imperial tollhouse;
1699: Stična Abbey;
1731: Jankovič family;
1734: Jožef Mihael pl.
Wallensberg;
1767: Filip Mihael pl.
Wallensberg, a son of Jožef Mihael pl.
Wallensberg;
1799: Janez Nepomuk Baraga;
1812: Frederick Baraga, a missionary and a son of Janez Nepomuk Baraga;
1824: Jožek Gressel, a brother in law of Frederick Baraga;
1842: Anamalija Gressel, the wife of Jožek Gressel;
1869: Karel Gressel, a son of Ana Malija and Jožek Gressel;
1863: Marija Gressel, a widow after Karel Gressel;
1896: Matija Hočevar and Franc Hren.

The last owner before the Second World War was a Czeck Evgen Evgen Šoulavy, after the war the castle was nationalized.
For some time, the castle hosted the Trebnje primary school; later it was turned into social housing.
Today, the castle is again in private hands.
It is believed that the castle was built around year 1000 by the Patriarchate of Aquileia and managed by their local vassal knights named de Treuen. Records attest that the castle's first vassal was Konrad de Treuen, who was then followed by Bernard, Henrik and Ulrik de Treuen between the years 1243 and 1245. A record from 1349 mentions the knight Hajncel, and Aquileian charters from 1358 refer to the knight Johannis de Treuen as the castle's overseers.
First mentions of the castle however date back to 1386 and 1436, and refer to it as Turn ze Treuen and turn zu Trefen mit dem purkchstal vnd dem pawhof, respectively.
According to a historian Valvasor, after the decline of knights of Treuen, the castle's ownership first passed to Counts of Ortenburg, and then to Counts of Celje, who owned the castle until 1456. With the demise of Counts of Celje, the castle was handed over to the Habsburgs as part of an inheritance agreement.
In the Early modern period the castle changed several hands. Written recordings list the following owners:
1601: Gabrijel Križanič;
1652: Jurij Jankovič;
1679: Wolf Konrad Jankovič;
1685: Matej Kowatschitsch pl. Schmiedhofen, who was a toll collector of provincial tollhouses in Jesenice and imperial tollhouse;
1699: Stična Abbey;
1731: Jankovič family;
1734: Jožef Mihael pl. Wallensberg;
1767: Filip Mihael pl. Wallensberg, a son of Jožef Mihael pl. Wallensberg;
1799: Janez Nepomuk Baraga;
1812: Frederick Baraga, a missionary and a son of Janez Nepomuk Baraga;
1824: Jožek Gressel, a brother in law of Frederick Baraga;
1842: Anamalija Gressel, the wife of Jožek Gressel;
1869: Karel Gressel, a son of Ana Malija and Jožek Gressel;
1863: Marija Gressel, a widow after Karel Gressel;
1896: Matija Hočevar and Franc Hren.
The last owner before the Second World War was a Czeck Evgen Evgen Šoulavy, after the war the castle was nationalized. For some time, the castle hosted the Trebnje primary school; later it was turned into social housing. Today, the castle is again in private hands.
Trebnje Castle