The Doncaster duo, who both represent Armthorpe’s Ultimate Taekwondo, are in a 14-strong squad for the Junior World Championships in Hammamet, Tunisia.
They have also claimed two of the three available spots at the Youth Olympic Games Qualifying tournament, also to be held in Tunisia.
Turner, 15, became a Cadet European Champion in 2016.
Yarrow, 17, won bronze at the 2015 Cadet World Championship and was named GB Cadet of the Year in 2014.
Romaine Bailey, GB’s development programme coach, said: “The Youth Olympic Games Qualifiers is a great opportunity for the athletes to go and secure a federation place for their respective weight categories – a chance that only some juniors are fortunate to have.”