At the age of eleven, Sancho was present at the Farewell Party of his uncle Bilbo, along with his father and grandfather on September 12, 3001 3A. Sometime on September 22, he went to Bag End to seek for a treasure he heard rumours about. Frodo tried to stop him, but Sancho already started excavating the pantry, where he thought he heard an echo.
Sometime after Frodo left the Shire, Sancho began to hold a deep hatred against the Sackville-Baggins and was one of those that watched Bag End, despite been a young kid. When his father joined the Shire Company with 800 hobbits to stand against the evil that was rising, Sancho wanted to go too, but he was too young and had to stay behind. After the war against Sauron ended, Sancho mourned his father's lost after he was slain during the Battle of Morannon.