The defender, who will not be available for the club's first match of the season against Southampton later this afternoon, is believed to have cost the Reds £12m.
Sports Mole takes a closer look at the latest arrival at Anfield.
The 22-year-old was born in Seville in 1992, and came through the youth ranks of his hometown club, whom he joined when he was 13, before making his senior debut in 2012 after a spell in the reserves.
Since then, Moreno has become an integral part of the Sevilla squad, making 44 appearances in all comeptitions for the La Liga side last season, as well as scoring three goals and helping the team to Europa League victory.
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Moreno's preferred position is at left-back, but he has proved himself a capable player down the wing, having played a more attacking role earlier in his career.
He made five starts in a midfield position for Sevilla last season, and bagged three assists during their successful continental campaign, stretching defenders with his precise crosses and impressive pace.
While his tackling and anticipation have earned him a strong reputation as a defender, Moreno's ball-control skills are also highly rated. He was in the top 10 for attempted and completed passes in the Europa League last season, and made 2.5 interceptions per game in Spain's top flight.
Moreno bid a tearful farewell to his Sevilla teammates after being pulled out of the squad for their Super Cup match against Real Madrid earlier this week, ahead of his impending move to Anfield.
It is always interesting to see how players adapt in a foreign league, particularly when they have spent their entire career with a club close to their home, but the Spain international's flexibility makes him an ideal player for Liverpool's system.
It is expected that Moreno will compete with Jose Enrique for a place in Liverpool's starting lineup, while also providing cover in midfield.