The 23-year-old Holland international has signed a five-year deal at St James' Park.
Magpies manager Alan Pardew told the club's official website: "We are delighted to secure the services of Vurnon."
Anita, who can also play as a full-back, joined the Ajax youth academy in 1999 and made his first-team debut in 2006.
Born on the island of Curacao, he had established himself as a key player at the Amsterdam Arena, winning back-to-back Eredivisie titles in 2011 and 2012.
Pardew added: "He is an exceptionally talented footballer with great technical ability, which is exactly what I'm looking at in a player.
"And, at 23 years old, we hope his best years are at Newcastle.
"He has come through the Ajax youth system which is world renowned for bringing up players the right way, and I am sure he will fit seamlessly into the squad of players we have here.
"Vurnon has done his pre-season, and indeed already played one competitive game, so he's up to speed and ready to play when I need him."