Origi came off the bench to score the winner in the 96th minute in Sunday's Merseyside derby at Anfield, profiting from a Jordan Pickford error.
But, having scored his third Anfield goal in the Merseyside derby, Klopp feels Origi can now become a major asset for the Reds.
"I said it to him, when I went to him on the pitch I had it in my mind. I've never forgot it since," Klopp told a news conference of the 23-year-old.
"Fouls and harsh tackles happen, but in his case it was so obvious that it [the injury] was a break in his development. At that time he was outstanding. After that, it took a long time before he felt absolutely nothing.
"In the Europa League final [in 2016] he was somehow ready but not completely pain free. Then there was a tournament [Euro 2016] when he couldn't really show up there.
"It all changed a little bit, you lose confidence and you don't play from here anymore. When Divock played at that time he was an unbelievable threat, he had speed, he was strong, remember the Dortmund game [in the Europa League] and stuff like that.
"So, it was always in my mind about Div, that night [against Everton]. And coming on tonight, he can finish that book and from now on everything will be fine again."
Origi's re-emergence gives Klopp an additional attacking option heading into the busy festive schedule, with Liverpool visiting Burnley in their next Premier League game on Wednesday.
Klopp substituted both Mohamed Salah and Roberto Firmino during the second half against Everton, but the Liverpool boss would not reveal his future squad-rotation plans, although Sadio Mane sustained a cut foot.
"We will see what we do, but it was such an intense game," Klopp added. "Sadio had the standout performance of the three [forwards]. Yes he had the chances and he didn't use them, but he was pretty much not [easy] to defend in one-on-one situations.
"He got better minute by minute. If you see now he is sitting in the dressing room and has a cut on his foot - 20 minutes from the end he got it, I don't know how it happened but it was a very painful thing.
"He didn't tell me, otherwise we may have changed [the substitutions] differently. Probably not. We will see how we line up in the next game. We only have to think about Burnley, not Bournemouth or Napoli or [Manchester] United or Wolves."