The wife of an Attican pharmacist and the mother of seven children, Karagianni worked to coordinate Greek resistance cells and their activities against the occupying Axis forces.

[2] As the occupation continued, the family grew increasingly involved in the burgeoning resistance movement against the-then Italian occupiers of Athens; this eventually resulted in the Lela, her husband, and her older sons joining the National Republican Greek League, commonly known by its Greek acronym EDES.

Lela formed her own cell within the wider movement, code-named "Bouboulina" in reference to her great grandmother Laskarina Bouboulina, a female Greek captain who had fought against the Ottoman Empire during the Greek War of Independence.

[3][1][4] Karagianni and her fellow partisans operated out of her husband's pharmacy in Athens and from a monastery in Megara.

However, she and other captured resistance members were executed by firing squad on the morning of 8 September 1944, just 34 days before Athens was liberated by Allied forces.