He was born in 714 in Jupille, in what is today part of Belgium, but then a part of the kingdom of Austrasia. His father was Charles Martel, Mayor of the Austrasian Palace, and his mother was Chrotrud (690-724). In 740 Pepin married Bertrada of Laon. Of their children, two sons and one daughter survived to adulthood.
On the death of his father in 741, power was passed down to his sons, Pippin and Carloman. Power may also have been intended for his illegitimate son, Grifo, but he was imprisoned in a monastery by his two half-brothers. Carloman, who by all evidence was a deeply pious man, retired to a monastery in 747. This left Francia in the hands of Pippin as mayor for the Merovingian king Childeric III. Childeric was unable to fulfill the most important function of a Frankish king, namely, to provide his warriors with a constant source of booty; Pippin was thus able to demonstrate to the leading men of the Franks that, as a better military leader, he was more qualified to be their king. He succeeded in obtaining the support of the papacy, which helped to discourage opposition. He was elected King of the Franks by an assembly of the Frankish leading-men and anointed at Soissons, perhaps by Boniface, Archbishop of Mainz.
During his reign, Pippin III's conquests gave him more power than anyone since the days of King Clovis. He added to that power after Pope Stephen II traveled all the way to Paris to anoint King Pippin in a lavish ceremony at Saint Denis Basilica, bestowing upon him the additional title of Patrician of the Romans. As life expectancies were short in those days, and Pippin wanted family continuity, the Pope also anointed Pippin's sons, Charles (born April 2, 742, eventually known as Charlemagne) and Carloman (born 751).
Pippin's first major act was to go to war against the Lombard king Aistulf as a partial repayment for papal support in his quest for the crown. Victorious, he forced the Lombard king to return property seized from the church. In 759, he drove the Saracens out of France with the capture of Narbonne and then consolidated his power further by making Aquitaine a part of his kingdom.