The English Premier League club paid £6.4 million to sign the Nigerian.
Gary Rowett, the new manager of Stoke City, described Etebo as an “energetic midfielder” and a great addition to the club.
“I and the management are really excited to have got the deal over the line for Etebo,” Rowett said on Wednesday.
“I’m looking forward to seeing him in a Stoke City shirt as I’m sure our supporters are too.
“Etebo is a very mobile and energetic midfielder further more and his age is fantastic. He has played in the top divisions in Portugal and Spain and, of course, he’s heading into the World Cup with Nigeria which will be an amazing experience for him.”
Tony Scholes, chief executive officer of the club, said: “We are delighted Etebo has chosen to join Stoke City, becoming our first signing of the summer.
“I’m particularly pleased that he took the time to look beyond our current league status and understand who we are as a club before choosing us ahead of current Premier League and Bundesliga clubs.”
Etebo spent last season on loan with La Liga’s Las Palmas.