Theodoros Baris was born in Pteri Drosias, in the Municipal Unit of Tritaia, Municipality of Erymanthos. He graduated from Erymantheia High School and holds a degree from a Pedagogical Academy. He has also obtained three postgraduate degrees in the fields of education and administration.

He has served in education in various positions of responsibility, while also developing significant trade union activity within the education sector. He has an extensive record of scientific, training, and writing work, and he is registered in the National Centre for Public Administration and Local Government (EKDDA) Adult Trainers Registry. He has excellent knowledge of new technologies and a very good command of the English language.

His involvement in local government began in 2006, when he was elected Municipal Councilor in the Municipality of Tritaia. During the period 2009–2010, he served as President of the Municipal Council. In 2010, he was elected Municipal Councilor in the Municipality of Erymanthos, and in 2014 he led the municipal group “Cooperation for Erymanthos,” which became the main opposition.

In 2019, he was elected Mayor of Erymanthos and was re-elected in 2023. He has served as a member of the Board of Directors of TEDK Achaia and the Supervisory Board of the Regional Union of Municipalities of Western Greece (PED Western Greece). Since 2019, he has been serving as Vice President of PED Western Greece. From 2019 to 2023, he was a member of the Civil Protection Committee of the Central Union of Municipalities of Greece (KEDE), and since 2024 he has been a member of the Education and Sports Committee.