Tekla Juniewicz was born as Tekla Dadak in Krupsko, Austria−Hungary (now Ukraine) on 10 June 1906. After Poland regained independence in 1918, Krupsko became part of Rozdol Commune, Stanislawow Voivodeship, Poland, and then became part of the Soviet Union after World War I when the border was shifted (Ukraine became independent in 1991). Juniewicz’s parents were Jan and Katarzyna Dadak, and she had two younger sisters, Rozalia and Katarzyna. Their father worked for Count Karol Lanckoronski, and their mother died during the First World War.
As a child, Juniewicz attended the school of Szarytki Sisters in Przeworsk, Poland, where she learned to sew, embroider, and cook. In Przeworsk, she met her future husband, Jan Juniewicz (22 years her senior), whom she married on 28 February 1927. After the wedding, they moved to Boryslaw, Poland, where she took a job in an earth wax mine. They had two daughters, Janina (born 1928) and Urszula (born 1929).
In November 1945, Juniewicz moved to Gliwice, Silesian Voivodeship, Poland, where her husband got a job in a mine. The couple were married until Jan Juniewicz died in 1980 at the age of 96. Tekla Juniewicz lived alone until she was 103 years old when her grandson Adam Stachowski moved in to assist her with her daily activities.
In June 2016, Juniewicz celebrated her 110th birthday. On her 113th birthday in June 2019, Juniewicz received a congratulatory letter from the Prime Minister of Poland, Mateusz Morawiecki. In August 2019, and later again in June 2022, Prime Minister Morawiecki visited Juniewicz in person at her home.
Juniewicz had been active all her life, even in her supercentenarian years. Some of her hobbies included reading, playing cards, watching movies and historical programs, working in her garden, and spending time with her family. Her active lifestyle may have been one of the factors to her longevity. She disliked being idle.
At the age of 116, Juniewicz was still able to walk short distances with assistance.
On 11 May 2020, Juniewicz became the oldest validated person ever born in present-day Ukraine, after surpassing the previous record of 113 years, 335 days set by Goldie Michelson.
On 18 February 2021, Juniewicz surpassed Venere Pizzinato-Papo’s final age of 114 years, 252 days to become the oldest validated person ever born in the Austro-Hungarian Empire.
Juniewicz became the last surviving European person born in 1906, following the death of Valentine Ligny on 4 January 2022. 22 days later, on 26 January 2022, Juniewicz became the last surviving validated person born in 1906, following the death of Yoshi Otsunari.
On 23 February 2022, Juniewicz surpassed Dina Manfredini’s final age of 115 years, 257 days to become the oldest validated emigrant ever.