The Belgian forward signs for £10 million, and will be loaned back to Lille for a season
The Belgian is said to have signed a five-year deal and will be loaned back to Lille for the 2014/15 season. He becomes the Reds' sixth signing of the summer.
Origi told the Liverpool website upon his arrival: "For me, it was my dream to play for a big club. I know Liverpool is a club with a great history, so for me it was perfect.
"I always watched Liverpool on the TV when I was small and if you see players like Gerrard and Sturridge, it's exciting to know that you're going to be playing with them."
Manager Brendan Rodgers has spoken highly of the youngster, suggesting he has the talent to go right to the top.
He said: "For me, he can be one of the most exciting talents in world football. I genuinely believe that.
"I've seen enough of him over the course of the last couple of seasons to think this is a kid who, coming into the right environment, can genuinely be world class."
Origi is unlikely to be Liverpool's last signing of the summer. Today they have signed a striker for the future, but it's likely they will try and sign one for the coming season before the transfer window shuts, along with one or two full-backs. Below are some photos of Liverpool's latest recruit: