Early life
Frodo was born to Drogo Baggins and Primula Brandybuck on September 22nd, Third Age 2968. He spent much of his youth at Brandy Hall in Buckland, the home of his mother's family. He was considered something of a rascal, particularly by Farmer Maggot from whom Frodo stole mushrooms. In 2980 when Frodo was only twelve years old he lost both his parents took a boat out onto the Brandywine River and drowned. With no siblings, Frodo was taken in by the Brandybucks to live at Brandy Hall until his cousin, Bilbo Baggins, adopted him and made Frodo his heir.

Later life
In 2989, Frodo came under the guardianship of Bilbo Baggins, whom he thinks of as his uncle (though Frodo was actually his first and second cousin once removed, since his mother is Bilbo's first cousin, and his father is Bilbo's second cousin). Frodo was 21 years old at the time, still far short of his coming of adult age at 33. The childless Bilbo chose Frodo as his adoptive heir, and brought him to live at Bag End.

Bilbo and Frodo share a common birthday on September 22 but Bilbo is 78 years Frodo's senior. At the opening of The Lord of the Rings, Frodo and Bilbo are celebrating their 33rd and 111th birthdays, respectively, on September 22, T.A. 3001.

War of the Ring
Frodo was entrusted with the keeping of the One Ring when Bilbo left for Rivendell after the celebration. Gandalf warned Frodo that the Ring must never be used and should be kept secret. (At the time, he was not yet certain that it was a Ring of Power.) Frodo kept the Ring hidden for seventeen years, until T.A. 3018, when Gandalf returned to confirm that it was indeed the One Ring. Gandalf sent him away with Sam Gamgee, who was Frodo's gardener and eventually his dearest friend. Together with Peregrin Took, Meriadoc Brandybuck and later Strider, they made it to the House of Elrond. There, at Elrond's Council, it was decided that the Ring must be destroyed by casting it into the Crack of Doom. A Fellowship was formed to protect Frodo as the Ring-bearer. His quest to destroy the Ring forms a large portion of The Lord of the Rings.

Frodo carried a small Elven sword (actually a dagger) called Sting and wore a coat of Dwarven chainmail made of Mithril under his clothes, both given to him by Bilbo. At Lothlórien, Galadriel gave him an Elven cloak and a phial carrying the light of the star Eärendil to aid him on his quest.

Two years after the Ring was destroyed, still troubled by the wounds he received during the War of the Ring, Frodo and Bilbo as Ring-bearers were given the right to travel to Valinor where, though remaining mortal, they might rest and be healed, together with Gandalf, Elrond and Galadriel. They boarded a ship from the Grey Havens and passed over the sea on September 29, T.A. 3021. Having no children of his own, Frodo left his estate and passed on the Red Book to Samwise Gamgee who followed Frodo across the sea 61 years later, following the death of his wife Rose (nee) Cotton.