Tinnuniel was born in Eregion, in the city of Ost-in-Edhil in the year 1677 S.A. Her birth happened at dusk, therefore her mother bestowed the name Tinnuniel on her.

Tinnuniel's early years were spent under the care of her mother Celebloth, an elleth skilled in the crafts of wood and metal whom had taken residence in the city to learn the art of silversmithing from the Mirdain of Eregion. Her father Calemir was often away on patrols along the borders of Lorinand. In the year 1697 Eregion was laid waste by the armies of Sauron at the end of the war between him and the Mirdain, in which Celebrimbor was slain and Ost-in-Edhil completely destroyed. That day, Tinnuniel's father was with his family, and managed to flee with his daughter in Lorinand when Ost-in-Edhil was sacked. Celebloth sadly fell with the city: she stayed behind to try and salvage as much of her craft as she could, but orcs and flames got her before she could get out of the city gates.

Thus Tinnuniel and her father came to live in the golden wood. Calemir resumed his duty as border guard, and for the remaining years of her youth Tinnuniel learned from him the ways of bow and sword. It was not her path to take though; she longed for a peaceful life, and in accordance to his daughter's wish Calemir relieved her from training. Through leisurely pursuits like literature and the art of cooking she found peace, and started traveling between elven settlements to always seek something  new to learn.