"I received an anonymous call late in the morning saying that my cello was inside a car in front of my house. I found it in the back seat," soloist Ophélie Gaillard told the AFP news agency.
One of the car windows was broken and the musician said she quickly grabbed the instrument, which is "in good condition", before notifying police.
An attacker had held her up at knifepoint outside her home on Thursday, forcing her to hand over the cello, as well as her mobile phone, before fleeing on foot in the northeastern suburb of Pantin.
"The theft was very violent, I have not been able to sleep for two days. I am so relieved to have found it. I'm coming out of a two-day nightmare -- it's a miracle," she said.
The police confirmed the cello had been found and a source close to the investigation by the unit in charge of armed robberies said: "It's not an instrument that can be sold to a fence on the corner".
After the robbery on Thursday last week, Gaillard appealed for help from the public on Facebook, posting pictures of the instrument.
"Help! My cello was stolen this evening in a red dark flightcase," soloist Ophélie Gaillard wrote, accompanied by pictures of the instrument.
She wrote that the cello, which was loaned to her by CIC bank and is valued at nearly 1.3 million euros, was made by Italian lute-maker Francesco Goffriller, the son of Venetian master cello-maker Matteo Goffriller.
The cello case also contained her bow, which she said was the work of acclaimed 19th-century French bowmaker Jean Pierre Marie Persoit.
In 2003, Gaillard was named the best new instrumental soloist at the French classical music awards.