Harry was onstage at the Kia Forum in Inglewood, CA Thursday night ... as a continuation of his "Love On Tour" when the wardrobe malfunction went down.

He was in the middle of singing "Music for a Sushi Restaurant" when he dropped low to his knees and ripped a huge hole near his crotch area, giving everyone an eyeful. As you can see, he was pretty stunned by the whole thing.

There's a debate about whether Harry was commando under his leather pants. We invite you to slo-mo, zoom in, enchance -- whatever -- and decide for yourself.

Nice bonus for the A-list celebs who pulled up for the concert -- Kylie Jenner, Trevor Noah, Julie Bowen and Ellen DeGeneres were there. Jennifer Aniston also witnessed the Styles family jewels coming out party ... and that's interesting because she's reportedly Harry's first celeb crush.

In true Harry fashion, he made the best of the moment ... and the crowd went wild at the funny mishap.

He told fans, "My trousers ripped. I feel I must apologize to a certain few of you right down in the front there. I mean this is a family show" ... before jokingly asking "Or is it?!"

He later put a towel around his waist as he continued to rock out onstage.