With Polish superstar striker Robert Lewandowski yet to play following his move from Bayern Munich for 50 million euros ($51 million), it was the 25-year-old Brazilian forward who led Xavi Hernandez's side to an easy win against the MLS club that is owned by former England international David Beckham.
Raphinha - who signed for 58 million euros from Leeds United earlier this month - first assisted Pierre-Emerick Aubameyang, who opened the scoring in 19th minute, and then extended the lead himself six minutes later with a nice left foot first touch strike.
Spanish teenage sensation Ansu Fati, who is slowly working his way back into form after a long layoff after a series of injuries, scored Barca's third right before halftime with another pass from Raphinha.
Barca came back to the second half with eleven substitutions but kept dominating and scored three more through Gavi, Memphis Depay and Ousmane Dembele.
It was Barca's first of four games in their U.S. preseason tour that will continue on Saturday with a Clasico against bitter rivals Real Madrid in Las Vegas.
"I think we are better than Real Madrid," Raphinha told reporters.
"I'm very happy to score my first goal and for things having turned out well in my debut. I felt very good. I hope I can continue like this.
"Of course I would like to score a goal against Real Madrid on Saturday. Scoring always gives confidence and if you do it against a team like Real Madrid even more so."
