John Jairo Ruiz Barrantes (born January 10, 1994) is a Costa Rican footballer who plays for Red Star FC in Belgrade, Serbia.
John Jairo began his career with C.D. Saprissa in 2011, scoring one goal against San Carlos on 11 September 2011. During the absence of Jairo Arrieta, Ruiz emerged as Saprissa's top striker in December 2011.
In January 2012, Ruiz signed a four-year contract with French side Lille OSC, and was playing with the reserve team until he was sidelined by injuries. In July 2012, Lille agreed a deal to send Ruiz to Belgian newly promoted Belgian Second Division team Royal Mouscron-Péruwelz on loan.
He currently plays in Ukrania for FC Dnipro.
Ruiz was selected in Costa Rica's squad for the 2011 CONCACAF U-17 Championship and he was named in the 2011 CONCACAF U-20 Championship. He participated in the 2011 FIFA U-20 World Cup finals in Colombia, where he scored Costa Rica's first goal of the tournament.