The Colombia international has left Udinese to replace Manolo Gabbiadini at the Genoa-based club.
Following the sale of Manolo Gabbiadini to Napoli earlier this month, Sampdoria were looking for striking reinforcements and have opted for the 23-year-old.
Udinese director of sport Christian Giaretta revealed that a deal to sell the South American attacker had been agreed.
"The Muriel project was meant to take a different path, but he didn’t deliver what we and many others expected,” the Italian supremo told Sky Sport Italia.
“The player supported this move and already has a basic agreement in place.
“As for Udinese, we’ll see what opportunities there are on the market. We have a competitive squad and the coach has various options at his disposal.”
Muriel announced himself at Udinese with 11 Serie A goals in 15 starts in 2012-13 after signing from Leece but has suffered from injuries and a lack of run of consistent games since.
The Colombian, who has been likened to former Brazil star Ronaldo in some quarters due to his ability to run with the ball, will be eager to get more playing time with the Genoa-based side.
Liverpool fans will not rue missing out on Muriel overly as he has not been at his best in recent months, but the Colombian could well be a player to keep an eye on if he regains full fitness and can string a run of games together for Sampdoria.