Seti was the son of Ramesses I and his queen, Sitre. He probably ruled as co-regent, evidenced by an inscription on a statue from Medamud. Seti married into his own military caste. His first wife was Tuya, who was the daughter of a lieutenant of charioteers. His first son died young, but his second son was Ramesses II.  There was also a daughter, Tia, and a second daughter named Henutmire, who would become a minor queen of Ramesses II.

This was truly a great period in Egypt, and perhaps the greatest in regards to art and culture. In the building projects that Seti I undertook, the quality of the reliefs and other designs were probably never surpassed by later rulers.  He is responsible for beginning the great Hypostyle Hall in the Temple of Amun at Karnak, which his son Ramesses II later finished.  Seti's reliefs are on the north side and their fine style is evident when compared to later additions.  

However, at Abydos, he built perhaps the most remarkable temple ever constructed in Egypt.  It has seven sanctuaries, dedicated to himself, Ptah, Re-Harakhte, Amun-Re, Osiris, Isis and Horus.  Interestingly, in this temple a part called the Hall of Records or sometimes the Gallery of Lists, Seti is shown with his son before a long official list of the pharaohs beginning with the earliest times.  However, the names of the Amarna pharaohs are omitted, as if they never existed, and the list jumps from Amenhotep III directly to Horemheb.  

Behind the temple at Abydos Seti build another remarkable structure known as the Osireion.  Completely underground, originally a long tunnel decorated with painted scenes from the Book of Gates led to a huge hall.  This whole structure with a central mound surrounded by canal water was symbolic of the origins of life from the primeval waters.  It was here that Seti rested after his death and before being taken to his tomb in the Valley of the Kings.

Other building projects included a small temple at Abydos dedicated to Seti's father, Ramesses I, his own mortuary temple at Thebes, and his best building project of all, his tomb in the Valley of the Kings.  This tomb, one of the few actually completed, was without doubt the finest in the Valley of the Kings, as well as the longest and deepest.  

Militarily, Seti let an expedition to Syria as early as his first year as king.  This was probably understandable, as he had also led campaigns to Palestine during the last months of his father, Ramesses I's rule. This, and other campaign during his first six years of rule are documented on the outer north and east wall of the great temple of Amun at Karnak. There is also a stele from Beth-Shan, for some time a major Egyptian center in Palestine, that records his early  campaign.  The attack was up the coast of Gaza, where he secured wells along the main trade route, and then taking the town, before pressing on further north.  He took the area up to Tyre before returning to the fortress of Tjel in the north east Delta.

There was a latter attack on Syria and Lebanon where he (and the Egyptians) fought the Hittites for the first time.  One scene at Karnak shows the capture of Kadesh, which would also be attacked later by Ramesses II.  He also fought campaigns against the Libyans of the western desert. We further learn that in year eight of Seti's reign, he had to crush a rebellion in Nubia in the region of Irem, where he carried off over six hundred prisoners.  However, apparently this was a minor problem as the campaign only lasted for seven days.

Seti's mummy is said to be the finest of all surviving royal mummies, though it was not found in his tomb.  Rather, it was found in the Deir el-Bahari cache in 1881.  Dockets on the mummy show that it had been restored during the reign of the High Priest of Amun, Heribor (1080-1074 BC) and again in year 15 of Smendes (about 1054 BC).