The designer is a 32-year-old French graphic artist, Jean Jullien, who lives in London.
Listening to the radio, he became horrified by the violence unfolding in his nation's capital and reached for his sketchpad.
"My first reaction was to draw something and share it," he told AFP. "It was spontaneous. I wanted to do something that could be useful for people."
"Given the scale of the violence, the peace-and-love symbol was essential. It was then quite an easy thing to combine it with the Eiffel Tower, the symbol of Paris," he added. "The two symbols fit together."
Jullien posted the combined symbol on his website and then tweeted it. Within hours, it was shared more 45,000 times and retweeted 76,000 times, including by the British underground artist Banksy.
At least 128 people were killed and several hundred were killed in coordinated gun-and-explosives attacks on a Paris concert hall, restaurants and the Stade de France stadium.
A similiar Internet phenomenon occurred after the January 7 attack on the satirical magazine Charlie Hebdo, in which 12 people were killed by jihadist gunmen.
He placed the image on social media, and within hours it was picked up around France and beyond, becoming the totem of nationwide rallies totalling an estimated four million.
