"He is a very good player on the ball, and hopefully he can produce the sort of passes that we missed last season. Certainly at home against packed defences when we could only draw important matches.
"Alberto has a winning mentality and great experience in both Serie A and the Champions League."
Aquilani, has played 11 times for Italy and has been with Roma, the club he supported as a child, since he was 16, making his debut as an 18-year-old under now England boss Fabio Capello.
"Aquilani has long been recognised as a top class talent in Italy, captaining his country at both Under 19 and Under 21 levels before establishing himself in the senior national side," said Benitez.
The Italian had an operation on his ankle injury in May after struggling with injury problems which restricted him to just 14 appearances for Roma last season.
The Reds had also been linked with Wigan's Lee Catermole and Valencia's David Silva.
Last summer a move for then Aston Villa midfielder Gareth Barry - now at Manchester City following a £12m summer transfer - fell through after Benitez was unable to sell Alonso to raise the sufficient funds for the deal.
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