The Norwegian scored one and set up another in a 3-1 win over the Catalan giants, who arrived as defending champions and lost a lone game all season.
Lyon got off to a magnificent start when Amandine Henry fired a superb effort from 35 yards past Barcelona keeper Sandra Panos to put the French ahead with just six minutes on the clock.
Barca were visibly withering under the pressure and Hegerberg doubled Lyon’s lead in the 23rd minute when she pulled her marker back to head home past Selma Bacha’s precise cross.
Hegerberg nearly scored three minutes later but was denied by Panos’ legs, but Catarina Macario extended Lyon’s lead just after the hour mark after driving home from a Hegerberg cross.
Barcelona gave themselves a glimmer of hope before the break when captain Alexia Putellas volleyed home in the 41st minute.
But despite a daring 50-yard lob from Patri Guijarro that hit the crossbar in the 58th minute, Barcelona were never able to score a second goal that could have made things interesting.
It would have been fitting for Hegerberg to have the last laugh, but his volley crashed into a post in the closing moments.
“We felt a strength from the whole team, I think everyone was 200 per cent motivated,” said player of the match Henry. “We had said from the start of the season that we wanted to win back this trophy, so we really wanted to make our mark on the pitch. And I think we did that more through mental strength than physical strength.
Additional PA Sport reporting.