The Belgian will be loaned back to Lille for next season.
Liverpool have completed the signing of 19-year-old striker Divock Origi from Lille for £10m.
Origi will be immediately loaned back to the French club for next season before starting his Anfield career in earnest in 2015.
He said: "I am very, very happy and delighted a club as big as Liverpool showed interest in me. I'm very excited.
"I know it's a club with a great history, great fans and a lot of great players. For me, Liverpool is one of the greatest clubs in the world and I'm very excited to be part of this great history."
Origi has scored six times for Lille since making his debut in 2013 and played a key role in Belgium's World Cup campaign, scoring the winner against Russia in the group stages.
Picture: LiverpoolFC.com
