The pair will front their own shows during the festive period on the radio station later this month.
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© Rex Features
Former Only Way Is Essex star Wright will host special editions of Party Classics on Christmas Eve and Christmas Day from 7pm.
He will then take on a permanent position as the host of the Friday and Saturday evening Club Classics show on the station at 7-9pm.
He said: "I've always listened to Heart from being a kid on the way to school and now getting ready for a night out, so to be presenting my own radio show on the station is a great honour.
"I had to pinch myself when I found out and I can't wait for my first show."
Klass will host her own special Myleene's Klass Christmas on Christmas Eve from noon.
X Factor act Ella Henderson will perform during the show alongside other musical guests.
She said: "I'm so excited to be joining the Heart presenter line-up.
"To be given my own show, a piano and the chance to work with some incredible people (as well as the seemingly constant supply of mince pies) is a lovely way to get in the Christmas spirit."
Global Radio's Director of Broadcasting Richard Park added: "We are thrilled with the new faces joining Heart this Christmas and New Year. What a great way to end a successful year and kick start 2013!"
Mark Wright is also expected to return to The Only Way is Essex during tomorrow night's episode (Wednesday, December 19).
