Though he is considered one of the greatest artists of the Northern Renaissance, little information exists about the childhood of Pieter Bruegel. All that is known for certain is that he was born Peeter Brueghel, into what many believe was a peasant family, in or near Breda in the Netherlands, between 1525 and 1530.
Bruegel's early artistic training consisted of an apprenticeship with the Flemish artist Pieter Coecke van Aelst. After Van Aelst's death in 1550, Bruegel moved to Antwerp, where he received his first commission, to assist in the creation of a triptych altarpiece for the glove-makers guild. The guild system was important to furthering artistic careers, and Bruegel's own professional life effectively commenced in 1551 when he was elected to the Guild of St. Luke, an Antwerp painter's association.

In 1552, Bruegel left Antwerp for an extended painting and research trip through Italy. Although he was not heavily influenced by the Italian-Renaissance style, the countryside he visited would have a great impact on the young artist, who would become well-known for his landscape works. Of particular significance were the Swiss Alps which Bruegel ventured through on his journey home. His first biographer Karel van Mander notes that the artist "swallowed all the mountains and rocks and spat them out again as panels on which to paint, so close did he attempt to approach nature in this and other respects."

Upon returning to Antwerp in 1555, Bruegel began working as an engraver for the Dutch artist Hieronymus Cock. The engravings which Bruegel produced for his employer often involved humorous themes and motifs, leading to his being known as "Pieter the Droll". Attempting to sum up the artist's engaging personality, Van Mander described Bruegel as "a very quiet and prudent man. He was a man of few words, but he was very droll in society, and he loved to make people jump with the unexpected jests and noises that he thought up."

The complex and fantastical scenarios depicted in many of Breughel's engravings, and in the few paintings which he created during the middle period of his career, led to comparisons with the famous Dutch painter Hieronymus Bosch (c. 1450-1516). The mercenary Cock capitalized on this reputation, selling a relatively unknown Bruegel engravings, Big Fish Eat Little Fish(1556), as a Bosch original in order to fetch a better price (Bosch had in fact died 40 years before the work was created).
While he is best known for his paintings, Bruegel did not embrace this medium until relatively late in his career, from around 1557 onwards. It was at this point that he developed his unmistakable compositional style, allowing him to shed comparisons with older Norther Masters such as Bosch, and to secure his status as a significant and in-demand artist. Numerous commissions were forthcoming, mainly from wealthy merchants and members of the church. In 1559, the artist changed the spelling of his name from "Peeter Brueghel" to "Pieter Bruegel."

In 1563, Bruegel married Mayken Coecke, the daughter of his former teacher Pieter Coecke van Aelst. There was a significant age difference between the two, the artist in his thirties and his bride - whom he had known since she was a child - only eighteen years old. Some controversy surrounded the couple's relocation to Brussels in the year of their marriage, with speculation that it might have been at the request of Mayken's mother, in an attempt to stop Bruegel's flirtatious relationship with a maid. The extent of the relationship between artist and servant remains a mystery, though there are accounts of humorous interactions between them, such as the story that Bruegel marked a stick with a notch every time the maid told a lie. She was so deceitful, it was said, that Bruegel ran out of room on his stick.

Despite its rocky beginnings, Bruegel's marriage marked the beginning of an artistic dynasty that incorporated the couple's two artist-sons, Pieter, later known as Pieter Brueghel the Younger, born in 1564, and Jan Brueghel the Elder, born in 1568. The young Pieter would go on to create many copies of his father's paintings, helping to ensure their international reputation long after the elder Bruegel's death, but also resulting in doubt over whether particular compositions were the work of father or son.

Late in his career, in addition to his many landscape paintings, Bruegel created various works depicting religious stories and scenes from everyday life. The latter proved to be more significant and enduringly influential, generating centuries of art-historical debate around the intended message of certain works. Some of the earliest writers on Bruegel, including Van Mander, took his paintings at face-value, as humorous expositions of the lascivious behavior of the serf class. More recent interpretation, however, has emphasized Bruegel's attempts to elevate that class through celebratory representation. As the art historians Rose-Marie and Rainer Hagen put it, "the fact that he should consider such a thing at all worthy of depiction distinguishes him from almost all of his contemporaries [...] The Italians and Romanists emphasized what distinguished man from the animal and plant world. Bruegel, in contrast emphasized their similarities, the nature, 'begotten, not made' element in man." William Dello Russo expands on this idea, writing that "Bruegel's vivid and lusty depictions of rural life can be seen as forming part of a growing sense of national identity."

The fact that Bruegel lived during politically troubling times has also compounded speculation over the interpretation of his work. In the mid-1500s, the modern-day Netherlands, along with Belgium and Luxembourg - collectively known as the Low or Netherlandish Countries - consisted of a series of provinces under the rule of the Hapsburg dynasty. In 1556, possession of the territories passed to King Phillip II of Spain, who attempted to impose a stricter form of Catholic rule, sending the Duke of Alba to lead a brutal military campaign in Brussels to suppress Protestant rebellion. According to art historians Rose-Marie and Rainer Hagen, Bruegel's consistent eschewal of the iconography of Catholic saints and martyrs, in spite of the religious focus of much of his work, can be seen as a coded rejection of the philosophy and bloodthirsty campaigns of the Counter-reformation. One story which suggests that Bruegel was quite conscious of the political significance of his work is told by Van Mander: not long before the artist's death, his biographer states, Bruegel asked his wife to burn certain works, believing that their content might put her in danger.

Little is known about the circumstances of Bruegel's death, though in 1569, the final year of his life, the city council of Brussels released him from the obligation of working with a guard of Spanish soldiers stationed in his home, suggesting that the politically subversive content of his work was well understood. No paintings exist from this year, implying that Bruegel died from illness, but there is no way of ruling out a more sinister explanation. In any case, Bruegel's relatively early demise, even for the period in which he lived, must be viewed as one of the tragedies of Renaissance art history.