The striker moves on a free transfer following the termination of his contract at Rangers and has signed a four-year contract with David Moyes' side
The 25-year-old moves to Goodison Park after agreeing a four-year deal with the Premier League club.
The Scot, who has played 15 games at international level, was delighted with his move to Merseyside stating that the club's history and proud supporters, as well as Premier League football, were big factors in his decision.
He told the Toffee's official website: "It is a great honour to be joining a club of Everton’s wonderful history and to have the chance to play with such a talented group of players in the world’s best league: the Barclays Premier League, in front of such a passionate group of fans.
"I look forward greatly to working with the Manager David Moyes and all the staff at Everton and working hard to deliver on the pitch to repay their, and the Chairman Mr Kenwright’s, faith and belief in me."
Toffees boss Moyes indicated that the player's versatility made him an attractive signing, with Naismith able to play up-front and on either flank in midfield, as well as the second-striker role.
"We are delighted that Steven has agreed to join us," the 49-year-old added. "He will be an excellent addition to the players we already have and we look forward to him being fit and ready to play at the start of the season.
"He is an established international who can play in a number of positions. He has a flexibility we always like in our players and which will hopefully prove to be very useful for us."
Moyes' new man will join with the rest of the squad for pre-season training later this week.