He was born in a dangerous time, which included the fall of Bosnia to the Ottoman Empire and the start of the Hundred Years' Croatian-Ottoman War.

His siblings were Beatrix, Ferdinand, Matija (Mátyás), Ivan Franjo (János Ferenc), Marija Magdalena (Mária Magdolna), Elizabeta (Erzsébet), Katarina (Katalin) and Eufrozina (Fruzsina).

Decades later, after the death of the King Matthias, the Hungarian crown passed to the Polish-Lithuanian House of Jagiellon with Vladislas II of Hungary in 1490.

[2] In 1496, by the influence of the Frankopan family, Christoph's sister, Beatrice de Frangepan, was married to John Corvinus, the illegitimate son of the deceased King Mátyás Hunyadi of Hungary.

In 1505, at 23 years of age, Krsto Frankopan entered the military service of Maximilian I of Habsburg, Archduke of Austria and King of the Romans.

He fought in the War of the League of Cambrai (1508–16) against the Republic of Venice and he won many battles including taking Devin and Pazin (1509).

In battle, he distionguished himself as a soldier and leader, and for this, in 1510, Maximilian I, now Emperor of the Holy Roman Empire, gave him Podgrad and some possessions of the city of Postojna, and appointed Krsto an imperial adviser.

In September of 1523, in the place of his sick father, Krsto went to Rome to ask Pope VI Hadrian to help Croatia fight the Turks.

[4] At the Diet of Hatvan, held on July 4, 1525, many nobles asked for Frankopan to be appointed Ban of Croatia but King Lajos (Louis) did not agree.

[5] In the summer of 1526, while Sultan Suleiman, with the army of the Ottoman Empire, marched to Hungary, King Lajos called on all the princes of Europe for help, but little came.

[7] On September 5, in a letter written in Croatian glagolitic script,[8] Frankopan informs Franjo Jožefić (Jozefics Ferenc), the Bishop of Senj, why he could not arrive at Mohács and that he regrets the loss of King Louis, but, in his opinion, the Hungarian nobles that risked their king and kingdom deserved the lesson they received from the Sultan.

Archduke Ferdinand of Habsburg, based on his marriage to Anna Jagellonica, the sister of King Lajos, immediately claimed the throne of Hungary for himself.

[13] On September 23, Krsto attended a Sabor in Koprivnica (Kapronca), where the nobles appointed him governor (captain-in-chief) of the counties of Baranya, Pozega, Somogy, and Zala.

Zápolya stayed in the royal city of Buda, and the Habsburg went back to his Austrian domains without giving up claim to the Hungarian throne.

On July 9, Ferdinand instructed his diplomat Johannes Habardanecz [hu] to, at all costs, prevent the meeting between Frankopan and war-leader Jovan.

On September 27, during the siege of the castle, while reconnoitring the fortress at Varaždin (Varasd), Frankopan was hit in the abdomen by a ball, probably from a wall gun (heavy arquebus).