They said they had discovered the remains of a housing settlement, jewellery, coins and several burial sites in the southern Peloponnese area.
Until now, archaeologists had a rough idea of where the city might have been located but had no tangible proof.
The items date from 4th Century BC to Roman times.
Excavation work around the modern-day village of Chiliomodi began in 2013, and "proof of the existence" of Tenea emerged in work carried out in September and early October this year, officials said.
Carefully-constructed walls as well as clay, stone and marble floors were uncovered. Around 200 rare coins, including one designed to pay for the journey to an afterlife, were also found.
Seven graves - including one containing the remains of a woman and child - were unearthed, adorned with vases and jewellery.
Lead archaeologist Elena Korka told the Associated Press that the discoveries suggested the citizens of Tenea had been "remarkably affluent".
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