The considerable degree of inaccessibility of the rocky massif was taken advantage of by the Czech nobleman Cenek of Vartenberg, who built a strong castle here in the years 1380 to 1390. He had a residential tower built on the two conspicuous rocks and at their foot it had massive, ten to thirteen metre high walls of a thickness of 1 to 1.8 meters constructed in three zones. The main wall of the fortifications was partially used for the building of palaces. These provided adequate dwelling comfort and, moreover, spacious storage rooms originated on their lower floors.
The founder of the castle Cenek of Vartemberk came from an important family of noblemen who owned large estates in northern and eastern Bohemia. He administered the local estate from 1367 to 1393, but thanks to his debts he was obliged to cede Trosky and the town of Bydzov to King Vaclav IV., who in 1398 presented the castle to Ota of Bergov, whose family made their way to Bohemia from Meissen. From 1388 Ota held the function of the supreme burgrave and thus also that of the commander-in-chief of the country's military forces. However, in the course of political events he headed the conspiracy of the rebellious Czech nobility against the King. He was a leader of the so-called Union of lords and as a member of the crown council he negotiated most actively with the King's brother, the Emperor Zikmund, who was endeavouring to become a ruler of the Czech lands. His son Ota, who inherited the castle in 1399, enlarged his estate and waged a number of disputes with his neighbours. He enjoyed the favour of the King and perhaps just in consequence he could be the terror of the surrounding yeomen and, although a catholic, also of the monasteries (he organized the plundering of Opatovice monastery).
Later he waged a tough fight against the Hussites and continued to cooperate with the Emperor Zikmund and German towns. In retaliation the military commander Jan Zizka conquered a number of castles on his estates as well as the town of Turnov and Valdstejn Castle.
In 1428 Trosky castle was the victim of a fire, after which the Hussites tried in vain to conquer it. Ten years later the large band of a robber knight, Sofa of Heffenburk and his comrade Svejkar made a successful night raid on the castle and occupied it. They killed the garrison and took Ota as their captive. Although they released him after a short period a provincial squad was dispatched to fight against the provincial malefactors. For three years it tried to conquer the castle, but it vain. Its defender were allegedly aided by a secret passage and the huge caves in the sandstone part of the rocks below the castle.
For several more years these uninvited owners were the terror not only of the surrounding population, but also of Lusatia. It was not until 1444 that the Zhorelec's and Zitava's forces of Sofa's expedition succeeded in killing, capturing and executing thirty-six of them. The remaining part of the band of robbers withdrew from Trosky and made its way to Valdstejn Castle. After their daparture its new heir, Jan of Bergov, sold Trosky to Jan Zajic of Hazmburk, who was the possessor of Kost and the adjoining estates. As Jan and his brother Oldrich of Hazmburk belonged among the nobility of rebelling against King George of Podebrady, the King besieged their castles. He conquered some of them and in 1469 the brothers surrendered Kost, Hruba Skala and Tosky. Later King George generously returned their confiscated property and castles to Jan Oldrich Zajic. In 1497 Trosky became the property of the Selmberks, in 1524 of the Bibrstejns and in 1554 of the Lobkowitz family. In those years the importance of the castle as a strong aristocratic seat came to the end.
During the ascendancy of the Smirice family from 1559 the region experienced a period of considerable economic flourish as the result of the founding of a number of ponds. In the course of the Thirty Years War Albrecht of Valdstejn gained possession of the estate and after his assassination in 1634 in Cheb both the estate and the castle remained in the hands of his heirs. Towards the end of the Thirty Years War the castle was for the last tim the scene of battles between the imperial and Swedish troops and in the same period a fire broke out once again. In 1820 the Valdstejns sold the castle to the count and knight Alpis Lexa of Ahrental, who, under the influence of the period of romantism, wanted to complete its construction and make the tower called Panna (Maiden) accessible as an observation point in the first part. In 1843 the staircase reached above the crown of the masonry of the palace, but the building work was brought to a halt by the count's death. In the period between the two world wars minor repairs were carried out by the club of Czech Tourists. Later the ruin fell under the administration of the Institute for the Care of Historic Monuments in Pardubice and conservation and safety measures were carried out on a larger scale.