He said the relic is strong evidence that the ancient Israelites were literate and could chronicle events centuries before the Bible was written. This could suggest that some of the Bible's accounts were based on written records as well as oral traditions - adding credence to arguments that the Biblical account of history is more than myth.
The shard was found near the stairs and stone washtub of an excavated home. It was later discovered to bear characters known as proto-Canaanite, a precursor of the Hebrew alphabet.
The Israelites were not the only ones using the proto-Canaanite characters, and other scholars suggest it is difficult - perhaps impossible - to conclude the text is Hebrew. However, Garfinkel based his identification on a three-letter verb from the inscription meaning "to do," a word he said existed only in Hebrew.
"That leads us to believe that this is Hebrew, and that this is the oldest Hebrew inscription that has been found," he said.
Hirbet Qeiyafa sits near the modern Israeli city of Beit Shemesh in the Judean foothills, an area that was once the frontier between the hill-dwelling Israelites and their enemies, the coastal Philistines. The site overlooks the Elah Valley, said to be the scene of the slingshot showdown between David and the Philistine giant Goliath, and near the ruins of Goliath's hometown in the Philistine metropolis of Gath.
Carbon-14 analysis of burnt olive pits found in the same layer of the site as the pottery shard helped archaeologists date it to between 1,000 and 975 B.C., the same time as the Biblical golden age of King David's rule in Jerusalem.
Archaeology has turned up only scant finds from David's time in the early 10th century B.C., leading some scholars to argue the Bible's account of the period inflates the importance of him and his kingdom. Some have even suggested his kingdom may not have existed at all.
But the fortified settlement where the writing was found contains indications that a powerful Israelite kingdom existed near Jerusalem in David's time, says Garfinkel.
If his claim is borne out, it would bolster the case for the Bible's accuracy by indicating the Israelites could record events as they happened, transmitting the history that was recorded in the Old Testament several hundred years later.
Modern Zionism has traditionally seen archaeology as a way of strengthening the Jewish claim to Israel and regarded David's kingdom as the glorious ancestor of the new Jewish state. As a result, finding evidence of his rule has importance beyond its interest to scholars.
The script, which Garfinkel suggests might be part of a letter, predates the next significant Hebrew inscription by between 100 and 200 years. History's best-known Hebrew texts, the Dead Sea scrolls, were penned on parchment beginning 850 years later.
The shard is now kept in a university safe while philologists translate it, a task expected to take months. But several words have already been tentatively identified, including "judge," "slave" and "king." The inscription was shown to other scholars at a peer presentation of the findings.
Some scholars are hesitant to embrace Garfinkel's interpretation, and his findings are already being wielded in the ongoing debate over whether the Bible - written hundreds of years after many of its events are supposed to have occurred - is more fact or legend. But the find is certain, at the very least, to prove useful in understanding the development of language and ancient alphabets.
Other prominent Biblical archaeologists warned against jumping to conclusions.
Hebrew University archaeologist Amihai Mazar said the inscription is "very important," but suggested that calling the text Hebrew might be going too far.
"The differentiation between the scripts, and between the languages themselves in that period, remains unclear," he said.
If the inscription is Hebrew, it would connect the Hirbet Qeiyafa settlement to the Israelites and make the text "one of the most important texts, without a doubt, in the corpus of Hebrew inscriptions," said Aren Maier, a Bar Ilan University archaeologist.
While the site is likely to add another "building block" to the historical record, archaeologist Israel Finkelstein of Tel Aviv University said the claims about it went beyond the strict boundaries of science.
Finkelstein, who has not visited the dig but attended a presentation of the findings, warned against what he said was a "revival in the belief that what's written in the Bible is accurate like a newspaper."