PSG host relegation battling Le Havre on Saturday
All of Kerr's goals were set up by England international Fran Kirby, who netted twice herself and also set up Guro Reiten for Chelsea's sixth goal.
"We were unbelievable for 60 minutes, the pace, intensity and movement. It was a great team performance across the board. Fran Kirby and Sam Kerr were unbelievable," Chelsea manager Emma Hayes told BT Sport.
The Blues, however, suffered a setback when Norway defender Maren Mjelde picked up a serious knee injury in the second half.
"Maren is a huge person in our dressing room, she is the person everybody looks up to. I hope she is OK. I know it's a bad one. I am devastated," Hayes said.