The event in Sant Boi will take place on the weekend of April 29-30.
Pentathlon GB are taking 12 youngsters to the event – six girls and six boys.
Mitchell, 16, is joined in the girls’ team by Olivia Green, Zoe Davison, Zoe Gowers, Emma Whitaker and Alexandra Bousfield.
The boys’ team will consist of Toby Price, George Budden, Nicholas Laws, George Case, Josh Hood and Kieran Harby.
The individual competitions will be held on Saturday, April 29 with a mixed relay the following day.