Karl Anton von Martini, Freiherr zu Wasserberg was born on August 15, 1726 in Revò near Bolzano. He was the second of eleven children born between 1725 and 1747. After the first basic education in the parental home as well as in the elementary school of Revò, Martini began the three-year study of philosophy in Trento in 1739. After these three years, Martini went to Innsbruck in 1741, where he began to study theology at his father's request, but never completed it. He also attended lectures in physics and in public law and the law of nations given by Paul Joseph Riegger. In 1747 Martini came to Vienna, where he graduated with a doctorate in law in 1753.

Due to his extraordinary talent, he was able to make the acquaintance of many influential personalities and thus received great appreciation and encouragement. One of them was Friedrich Wilhelm Graf von Haugwitz, who employed Martini as his secretary from summer 1750 to early 1752. In addition to this position, Martini was a tutor for Graf Sigismund von Khevenhüller, who was destined for a diplomatic career. Khevenhüller was to accompany Christoph Graf Migazzi, who was sent to Madrid as a representative of the Empire as well as to Tuscany to negotiate the treaty of Aranjuez. Martini had been chosen to accompany Khevenhüller as his secretary. On February 7, 1752, the great journey began. After a first stop in Prague, the journey continued through Germany, the Austrian Netherlands, France, Italy and Spain, where Martini spent 13 months serving at the imperial embassy in Madrid. During this trip he was able to deepen his knowledge of natural law and also of the world.

In 1754, probably on Riegger's recommendation, Martini was appointed to fill the newly created professorial chair of natural law connected with the institutions and the history of Roman law at the University of Vienna. Martini's return to Vienna to start the professorship marked the beginning of his writing career. However, Martini was not only known as a scholar and teacher, but he held many important offices as a practical jurist, which, among other things, affected his literary activity as well as his teaching position.

As early as 1758, Martini became a member of the Hofkommission in Zensursachen (Court Commission for Censorship), as well as of the Studienhofkommission (Court Commission on Education) the following year and subsequently took over its chairmanship in 1762. Simultaneously, Martini became private tutor to the children of the Empress Maria Theresia from 1761 to 1763. The year 1764 was marked by Martini's newly attained position as Hofrat (court councillor) of the Oberste Justizstelle (Austrian Supreme Court), subsequently he took part in all important legislative work. In particular, in 1773 Martini became a member of the Kompilationshofkommission (Compilation Court Commission), the institution in charge of drafting the codification of Austrian civil law. In February 1774 Martini joined the böhmisch-österreichische Hofkanzlei (Bohemian and Austrian Court Chancellery) as a Hofrat. Here he was entrusted with educational matters and the abolition of the Order of the Jesuits. At his own request, Martini finally returned to the Oberste Justizstelle where he became a Staatsrat (state councillor) in domestic affairs in 1782. There Martini was also involved in the implementation of a curriculum approved by Maria Theresia in 1773, which he had been formulating from 1760 to 1762 at first in the role of a mere member, later in the position of a chairman of the Studienhofkommission. Ultimately his progressive educational plan failed due to the resistance of the conservative bureaucracy.

After handing over the professorship to his favourite student Franz von Zeiller in 1782, Martini was sent to Milan to implement the Josephine judicial reform in Lombardy as well as in the Austrian Netherlands. His subsequent return to Vienna was distinguished by his appointment to vice president of the Oberste Justizstelle on February 24, 1788. Two years later, Martini was entrusted with the presidency and the direction of the completely new Hofkommission in Gesetzessachen (Court Commission in legislative affairs), where, as chairman, he initially led the further work on the codification of civil law based on the preliminary drafts of his student Johann Bernhard Horten, “Entwurf Horten”. He was relieved from this position on March 10, 1797. Earlier, on April 16, 1792, Martini was appointed the Second President of the Oberste Justizstelle and kept this position until his death.

From 1773 and for more than two decades, Martini played a leading role in drafting the codification of Austrian civil law. That is why the resulting draft is known as "Entwurf Martini" in jurisprudential literature. It was introduced as "Westgalizisches Gesetzbuch" in 1796 and in extended to East Galicia and Bukovina in 1797. However, the draft was reviewed by a Revisionskommission, whose slow work led to a new Court Commission for legislative affairs, composed of members of the two old institutions. A dispute about the the presidency led Martini to resign from the Gesetzgebungskommission in 1797. According to Franz von Zeiller, Martini was also weakened by age, innumerable arduous tasks and the various hostilities he had suffered in the process, and consequently became incapable of any intellectual effort. Living in seclusion, he died in Vienna on August 8, 1800.

Martini's works on natural law remained influential in the Habsburg monarchy for decades and are most closely related to his activities as a university professor: his De lege naturali exercitationes sex (first edition 1766) was initially published in Latin; its individual parts had been published separately in the years before, and it experienced numerous new editions in the following years. This publication had been preceded in 1762 by the textbook De lege naturali positiones in usum auditorii vindobonensis, which was followed in 1768 by his Positiones de iure civitatis in usum auditorii vindobonensis. These works, too, went through a series of new editions and in 1783-84 a four-volume compilation from them was translated into German as Lehrbegriff des Natur-, Staats- und Völkerrechts. Until 1848, the university course on the ius publicum naturale was based on the Positiones de iure civitatis. From 1809/10 onwards, the translation by Franz von Egger was used. It significantly revised Martini's original text and was based also on Franz von Zeiller. For example, "innate natural rights" were paraphrased as "rights of the subjects" (Rechte der Staatsunterthanen).

Karl Anton von Martini is considered one of the most important Austrian scholars in the field of natural law. However, the assessment of his work varies greatly, especially in comparison to his contemporary Joseph von Sonnenfels and to his student Franz von Zeiller. 

Research unanimously emphasises the influence of Samuel Pufendorf, and it is commonly thought that especially Christian Wolff had a formative influence on Martini (Carboncini, 2018, p. 472). Both points need to be further developed. In any case, Martini undoubtedly takes a deistic standpoint, in that the physical world as a whole, and thus ultimately also law, is traced back to an act of God's creation. For Martini, natural laws are mathematical truths that are accessible to man through the use of his reason and as such are immutable and eternal.

Unsurprisingly, Martini sees the social contract as the basis for the emergence of state and society, but he does not see the political contract as the source any right to resist the sovereign. At most, the subject may passively refuse to obey the prince who has mutated into a tyrant.

The ruler is required to realise the "general welfare" or the "common best" and is bound only to this end in all his actions. In doing so, it is exclusively up to him to define the bonum commune and the means to achieve this end. Although the common good as the purpose of the state represents a theoretical limit to the actions of rulers, the fact that the monarch has a monopoly on the interpretation of the common good and the way to achieve it means that his rule remains de facto unrestricted. The same applies to "civil freedom", which for Martini, as for his contemporaries, denotes the residue of the original "natural freedom" in the state of socialisation. These areas of freedom are, of course, open to interventions of the state insofar as the latter may restrict "civil freedom" for reasons of the common good. Opinions are sharply divided concerning Martini’s position in the history of human rights, with some considering him a pioneer (e.g., Heinz Barta and Dieter Grimm), others finding this idea difficult to square with Martini's insistence that it is up to the sovereign to demarcate individual spheres of freedom (e.g., Herbert Kalb).