She was born and raised in the Djursholm district of Danderyd, a northern suburb of Stockholm, and is an alumna of the musical magnet schoolRytmus Musikergymnasiet. She formed the rock band Tremblebee in 2006. Following the disbanding of Tremblebee, she pursued a career in songwriting and earned a publishing deal with Warner/Chappell Music in 2011. Working with producers Alexander Kronlund, Max Martin, and Xenomania, she became a successful songwriter recording and independently releasing her own compositions.
Ebba Tove Elsa Nilsson was born on 29 October 1987 in Stockholm, Sweden. Her mother is a psychologist and her father is a businessman. She has one older brother. Her lifelong nickname and adopted stage name, Tove Lo, was given to her at age three by her godmother because of her love for lynxes (singular: "lo" in Swedish). She explained; "There was this lynx at a zoo that was called Tove, and that I totally fell in love with. It was my dear godmother who decided to call me Tove Lo, after that lynx. It stuck." Lo grew up in the affluent Djursholm district of Danderyd Municipality, just north of Stockholm. She describes her childhood as being "very protected" and her family as "pretty posh". She excelled in social sciences at school and grew fond of literature, writing poetry and short stories.
In an interview with the BBC, she explained, "Growing up so safe, I think I was looking for something else".
Lo then developed a love for music and formed a girl band with her friends. With the band, she wrote her first song at age 10 or 11. By age 15, Lo had written a compilation of lyrical content which "nobody ever saw" and had performed twice on stage, before enrolling at Rytmus Musikergymnasiet, a musical school in Stockholm. During her time at Rytmus, Lo developed a friendship with Caroline Hjelt, who would later form the Swedish duo Icona Pop. After two years, Lo graduated from the school and felt assured that her career would be in music despite her parents preferring otherwise.