Porphyry's parents were Phoenician, and he was born Malchus ("king")For connotations of West Semitic MLK, see Moloch; compare theophoric names like Abimelech. in Tyre. His teacher in Athens, Cassius Longinus, gave him the name Porphyrius ("clad in purple"), a punning allusion to the color of the imperial robes. Under Longinus he studied grammar and rhetoric. In 262 he went to Rome, attracted by the reputation of Plotinus, and for six years devoted himself to the study of Neoplatonism. Because of this he became suicidal. On the advice of Plotinus he went to live in Sicily for five years to recover his health. On returning to Rome, he lectured on philosophy and completed an edition of the writings of Plotinus (who had died in the meantime) together with a biography of his teacher. Iamblichus is mentioned in ancient Neoplatonic writings as his pupil, but this most likely means only that he was the dominant figure in the next generation of philosophers. The two men differed publicly on the issue of theurgy. In his later years, he married Marcella, a widow with seven children and an enthusiastic student of philosophy. Little more is known of his life, and the date of his death is uncertain.

Porphyry is best known for his contributions to philosophy. Apart from writing the Aids to the Study of the Intelligibles (Sententiae Ad Intelligibilia Ducentes), a basic summary of Neoplatonism, he is especially appreciated for his Introduction to Categories (Introductio in Praedicamenta), a very short work often considered to be a commentary on Aristotle's Categories, hence the title. According to , however, the correct title is simply Introduction (????????,)(Isagoge), and the book is an introduction not to the Categories in particular, but to logic in general, comprising as it does the theories of predication, definition, and proof. The Introduction describes how qualities attributed to things may be classified, famously breaking down the philosophical concept of substance into the five components genus, species, difference, property, accident.

As Porphyry's most influential contribution to philosophy, the Introduction to Categories incorporated Aristotle's logic into Neoplatonism, in particular the doctrine of the categories of being interpreted in terms of entities (in later philosophy, "universal"). Boethius' Isagoge, a Latin translation of Porphyry's "Introduction", became a standard medieval textbook in European schools and universities, which set the stage for medieval philosophical-theological developments of logic and the problem of universals. In medieval textbooks, the all-important Arbor porphyriana ("Porphyrian Tree") illustrates his logical classification of substance. To this day, taxonomy benefits from concepts in Porphyry's Tree, in classifying living organisms: see cladistics.

The Introduction was translated into Arabic by Abd-All?h Ibn al-Muqaffa? from a Syriac version. With the Arabicized name Is?gh?j? (????????) it long remained the standard introductory logic text in the Muslim world and influenced the study of theology, philosophy, grammar, and jurisprudence. Besides the adaptations and epitomes of this work, many independent works on logic by Muslim philosophers have been entitled Is?gh?j?. Porphyry's discussion of accident sparked a long-running debate on the application of accident and essence.

Porphyry is also known as an opponent of Christianity and defender of Paganism; his defense of traditional religion, Philosophy from Oracles, written before the persecutions of Christians under Diocletian and Galerius, set out the basis for them:

"How can these people be thought worthy of forbearance? They have not only turned away from those who from earliest time have been thought of as divine among all Greeks and barbarians... but by emperors, law-givers and philosophers... all of a given mind. But also, in choosing impieties and atheism, they have preferred their fellow creatures. And to what sort of penalties might they not be subjected who... are fugitives from the things of their Fathers?"

Whether or not Porphyry was the pagan philosopher opponent in Lactantius' Divine Institutes, written at the time of the persecutions, has long been discussed. A Christian version of Philosophy from Oracles has been attributed to Porphyry. The attribution was accepted by Eusebius and appealed to by apologists like Theodoret. St. Augustine was one of the first to reject it. Dr Nathaniel Lardner rejected the attribution in the 18th century.

Of his Adversus Christianos (Against the Christians) in fifteen books, only fragments remain, as quotations adduced in order to be refuted. In it, he famously is quoted as having said, "The Gods have proclaimed Christ to have been most pious, but the Christians are a confused and vicious sect." Counter-treatises were written by Eusebius of Caesarea, Apollinaris of Laodicea, Methodius of Olympus, and Macarius of Magnesia, but all these are lost.

Porphyry's identification of the Book of Daniel as the work of a writer in the time of Antiochus Epiphanes (2nd century BC), is given by Jerome. Augustine and the 5th-century ecclesiastical historian Socrates of Constantinople, assert that Porphyry was once a Christian.

Porphyry was also opposed to the theurgy of his disciple Iamblichus. Much of Iamblichus' mysteries is dedicated to the defense of mystic theurgic divine possession against the critiques of Porphyry.

Porphyry was, like Pythagoras, an advocate of vegetarianism on spiritual and ethical grounds. These two philosophers are perhaps the most famous vegetarians of classical antiquity. He wrote the De Abstinentia (On Abstinence) and De Non Necandis ad Epulandum Animantibus (roughly On the Impropriety of Killing Living Beings for Food), advocating against the consumption of animals, and he is cited with approval in vegetarian literature up to the present day.

Porphyry also wrote widely on astrology, religion, philosophy, and musical theory. He produced a History of Philosophy (Philosophos historia) with vitae of philosophers that included a life of his teacher, Plotinus. His life of Plato from book iv exists only in quotes by Cyril of Alexandria. His book Vita Pythagorae on the life of Pythagoras is not to be confused with the book of the same name by Iamblichus. His commentary on Ptolemy's Harmonics (Eis ta Harmonika Ptolemaiou hypomn?ma) is an important source for the history of ancient harmonic theory.