The 18-year old midfielder came on in the 71st minute for Hector Jimenez and was able to score a brilliant goal in the 87th minute to snatch a point from Vancouver Whitecaps who had led 2-0 with nine minutes to go.
David Beckham netted for the Galaxy in the 81st minute before Villareal gained control of Juninho's pass before turning his marker and sending a wonderful left-footed effort into the top left corner from the edge of the area.
The young gun was delighted after the match but almost lost for words when asked to talk about his first MLS goal.
"I don't even know man," he said in a postgame interview with Galaxy broadcast partner KDOC.
"It was overwhelming, I was excited - I was nervous, but once I got a few touches on the ball, everything just slowed down for me.
"There's not a lot of words I can say to describe."
The draw allowed the Galaxy to remain fifth on the Western Conference table, four points behind fourth-place Vancouver and third-placed Seattle Sounders.