BBC Radio 1 announced today 1Xtra presenter Letitia as the new host of Sunday Surgery, the station's weekly phone-in show dealing with emotional, sexual and health issues for its young audience.
Emma B, who joined Radio 1 in 1998 and has presented the Surgery since 2000, will leave the station at the end of March.
Dr Mark Hamilton will continue to co-host the show and Letitia will continue to host her show every Saturday and Sunday (2.00-5.00pm) on 1Xtra.
Andy Parfitt, Controller of Radio 1, said: "I'm really happy to welcome Letitia to Radio 1 and she's bound to do a great job.
"The Surgery is a hugely important programme and is the front for all of our social action campaigns.
"Emma has been brilliant as the host for the last five years and I wish her all the best in her future career."
Letitia said: "This is an amazing opportunity and I can't wait to get started. There isn't a show like Sunday Surgery anywhere else on the radio and it's a real honour to be asked to front it and continue to take it forward."
Emma B said: "I've had a wonderful time presenting Sunday Surgery and am very proud of what we have achieved.
"I now feel ready to move on to work on new and exciting TV projects but I will be keeping my toes in the radio water with my Top Of The Pops World Service show and regular depping on 6 Music."