The 29-year-old’s arrival will boost Newcastle‘s attacking options and will give Rafa Benitez some relief after failing to do much business in the January transfer window.
Discussing his move, Slimani said: “It’s a great thing for me and for Newcastle.
“I’m happy to be here. Hopefully I can come here and be able to give them a hand.
“Knowing the power of the fans and crowd here and how great they are, and also speaking to the manager, it gave me the confidence that this was the right choice.”
And Benitez said: “Slimani is a player with experience in the Premier League, and obviously we were looking for that.
“He is a player who can fight with defenders, challenge and score goals.
“Hopefully he can give us some experience and some different characteristics to the strikers that we have at the moment.”
Slimani struggled during his time at Leicester and managed five goals in 17 appearances this term.
At international level, the 29-year-old has fared a lot better, scoring 26 goals in 55 outings.
Meanwhile, the Magpies let goalkeeper Freddie Woodman join Aberdeen on loan for the rest of the season.