Hosted by CBBC presenter Cell Spellman, the new show will split into two parts, one devoted to new pop music with the other playing number one hits.
The 19-year-old called his new posting "a privilege and an honour".
The Official Chart will move to Fridays on 10 July to coincide with a new global release day for music.
Presenter Greg James will kick off at 16:00 BST every Friday as 45 countries launch New Music Fridays.
Spellman made his Radio 1 debut in 2013, standing in for Dan and Phil on Radio 1's Request Show. He presents CBBC's Friday Download and the CBBC Official Chart.
Radio 1 controller Ben Cooper said: "Radio 1 and CBBC are changing the way radio and TV work together to create great content for young new music fans on their radio and phone.
"Cel has proven how influential he is to young audiences and I can't wait for him to start."
Spellman said: "The best station on national radio has been responsible for introducing me to so much incredible and varied music over the years, I just hope I can return the favour and help make those car journeys a little more memorable for the listeners with a mix of fun, top tunes and a little bit of cheeky chat!"
Radio 1 has announced a new Sunday show which will replace the current Official Chart slot when it moves to Fridays next month.