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.
Juniewicz died from complications of a stroke she had one day prior in Gliwice, Silesia Voivodeship, Poland, during the early morning hours of 19 August 2022, at the age of 116 years, 70 days. According to her grandson Adam, Juniewicz had been in good health and spirits until the day before she died. Her funeral was held four days later on 23 August 2022, in her hometown of Gliwice.
Juniewicz is the first recorded supercentenarian from Poland’s Silesia Voivodship. She became the oldest living person in Poland, following the death of 111-year-old Jadwiga Szubartowicz 20 July 2017.
On 24 April 2018, Juniewicz became the longest-lived person ever documented in the history of Poland after surpassing the previous record of 111 years, 317 days set by Wanda Wierzchleyska. On 10 June 2018, Juniewicz became the first Polish person on record to reach the age of 112. She subsequently became the first Pole to reach the ages of 113, 114, 115, and 116 (in 2019, 2020, 2021, and 2022 respectively).