England Under-21 international midfielder Henderson, 20, has signed "a long-term deal" on Merseyside. He agreed personal terms and visited the Reds' Melwood training complex on Wednesday before undergoing a medical. The highly-rated starlet has moved for an undisclosed fee, described as "substantial" by Sunderland's website, with reports suggesting it could be up to £16million rising to nearly £20million depending on adds-on and clauses. Henderson has spoken of his excitement at signing for Liverpool, telling the club's website: "I'm over the moon, overjoyed to be here and I'm really looking forward to it. "I was flattered to know Liverpool were interested in me and, once I knew, it was a massive decision for me to make but also a massive opportunity. "Obviously it's hard to leave your local club. I'm a Sunderland lad, I've supported them all my life. "But I'm really looking forward to the future now and obviously this is a massive opportunity for me. I'm really excited by it." A statement from Liverpool read: "Liverpool Football Club have completed the signing of Jordan Henderson after the 20-year-old passed a medical and agreed personal terms. "Henderson travelled to Merseyside on Wednesday after a fee was agreed with Sunderland. He then underwent a medical examination in Liverpool before signing a long-term deal." Henderson is Liverpool's first signing of the summer and - following the big-money captures of Andy Carroll and Luis Suarez in January - the third high-profile new recruit since Fenway Sports Group's takeover of the club and Kenny Dalglish's return as manager last season. Currently part of the England Under-21 squad who get their European U21 Championship campaign under way in Denmark this weekend, Henderson won his first senior international cap against France last November and his value has soared over the past year, despite a recent dip in form. The Sunderland youth academy graduate made his Black Cats debut in a 5-0 defeat to Chelsea in November 2008. In total he has made 79 appearances for the Wearsiders, scoring five goals, and he also spent a spell on loan at Coventry in the 2008-09 season. He said: "My family are all Sunderland fans as well, and it's pretty tough because I've had some great years there. "I've been there since I was seven and I'll definitely miss it but, like I say, I'm looking forward to playing for Liverpool now." Henderson admits he cannot wait to link up with midfield colleague Steven Gerrard. "He is one of the best players in the world, you want to be playing with him and training with him to try to improve yourself as a player," Henderson said. "I've trained with him once (for England) and he was unbelievable, to be honest. I'm looking forward to it, and there are other good players here who can help me as well. "Steven has been a massive, massive player for Liverpool for years now and he still is. Hopefully I can learn a lot from him." It had been thought Liverpool striker David Ngog might travel in the opposite direction as part of the transfer. He remains at Anfield for now, but Reds director of football Damien Comolli has indicated the 22-year-old could still be headed for the Stadium of Light. "Sunderland have had a strong interest in David, so we've agreed to let David speak to Sunderland about his future to see if he's interested in going there," Comolli said. "They've expressed a strong interest, so we'll see what's next for him." Comolli conveyed his delight at the conclusion of the Henderson deal and insisted Liverpool had not paid over the odds. "I'm very pleased because he was one of the targets we had and when you get your first target it's always a good sign because you think the others will come through as well," Comolli said. "We are very, very pleased. He has got all the skills technically that we needed. "He's good with the ball, he's creative, he's got good passing, he's physically very good. "That's everything we wanted in a midfielder and he's versatile as well. For Kenny, he will be the player we wanted. "On the fee, I've read and heard a lot of things. There was a lot of speculation on how much we would pay for Jordan and none of the figures I've seen are correct so far. "We've paid a price that we are comfortable with, otherwise we would not have done the deal." Dalglish is likely to continue doing business in the transfer window as he attempts to rejuvenate his squad this summer. Liverpool are believed to retain interest in Blackpool midfielder Charlie Adam, while Ipswich youngster Connor Wickham is thought to be another target.