The 18-year-old has signed a long-term deal to move to the Anfield giants.
Aberdeen will receive a reported initial £4.2million with the fee rising to anywhere between £6.5million and £8million.
The transfer follows a breakthrough season for Ramsay, who became the club's first-choice right-back, winning the Scottish Football Writers’ Young Player of the Year award for his performances which brought about one goal and a number of assists.
Ramsay said he was “buzzing” about the move to Liverpool and called it a “dream come true”.
"It was a dream come true to play for Aberdeen, and now to be at one of the biggest, if not the biggest club in the world, it's a massive achievement and I’m looking forward to trying to show the fans what I’ve got," he said.
Ramsay is a boyhood Aberdeen fan, watching the team with his dad before going on to play and score for the team.
“My dad and I used to go to all the Aberdeen games in the Merkland Stand and it was always my dream to play for the club, and it was his dream for me, so to go on and do it, I still don’t think it has sunk in for my dad, or for me to a degree.
“All of my youth academy coaches helped me a lot along the way, every single one of them. They’ve all been brilliant in their own way. There are a lot of young players coming through the Youth Academy and there is a pathway there so I am sure if these young boys stick in, they can go on and become the next big thing.
“I want to say a special thank you to the fans. Since my debut they’ve always been brilliant with me, very supportive and I appreciate that a lot. I know it wasn’t the best season for us on the pitch and it was difficult for the fans, but they have been excellent with me and hopefully I will see them again one day.”
Aberdeen hope Ramsay will be one of many coming through the club's youth system with director of football Steven Gunn calling the transfer a “clear sign of the continued commitment to youth development” and “is recognition of the progress of the Academy over the last few years under the previous stewardship of Neil Simpson and now Gavin Levey”.
Manager Jim Goodwin added: “There is no doubt this is an exciting opportunity for Calvin and his family. The AFC youth academy deserves a huge amount of credit for developing Calvin and it is testament to the pathway here at the club that Calvin was given his debut in the first team, and not only that, was able to hold his own in the team last season.
“Liverpool are very lucky, they are getting a promising young talent. His stats in the first half of last season were amongst the top for full backs in the world. We certainly had high hopes for him and I’ve no doubt he will go from strength to strength in a very good team at Liverpool.”