Manager Brendan Rodgers praised the 20-year-old rising star upon completion of the transfer:
Reds boss Brendan Rodgers said: "We are all delighted that Luis has decided to join Liverpool.
"He has the correct footballing profile and mentality to be a Liverpool player.
"I look forward to working with him to develop his talent and he joins a group of young exciting players at our club."
The deal will become official once it receives international clearance. Terms of the transfer fee and the forward's new contract were not included in the official announcement.
Alberto spent last season with Barcelona's B squad on loan from Sevilla. It was a chance for him to receive consistent playing time while playing alongside a talented group. His strong play must have captured the attention of Rodgers.
The Spanish youth international scored 11 goals and chipped in 17 assists in 38 appearances. Liverpool hope his development continues to a point where he can put up those type of numbers in the Premier League, where the defenses are much tougher to navigate.
ESPN passed along comments from Alberto after the agreement was made official. He credited Rodgers as the main reason he decided to accept a move to Anfield.
"I came to the club because of the manager," Alberto said. "I came here because of the style of football he plays.
"I feel very excited, I've never felt so excited before but I'm very happy. I think I am the happiest man on earth.
"I was surprised [when Liverpool showed interest in me]. You never expect this to happen to you. But as the deal moved forward, I became very happy and I wanted to come to Liverpool."
Alberto possesses an intriguing skill set. He combines above-average pace with plenty of creativity, a solid work rate and an improved scoring touch. Liverpool must hope those raw skills eventually turn into Premier League ability.
There's certainly going to be a transition period. Even though Barcelona fields a very competition B squad, the level of competition is still far from the EPL. So Rodgers will probably work him in slowly as he gains valuable experience.
Liverpool won't be concerned if he doesn't make an immediate impact since it's more of a signing for the future. That said, it probably won't take long for Alberto to start making his presence felt for the Reds.