Jack Jakaboski studied Digital Music and Sound Arts at the university before joining the London school which has trained the likes of Jacqueline du Pré, Sir James Galway and Sir George Martin.
Jack said: "I enjoyed my course at Brighton. I regret not getting as much out of it as I should have done…but it definitely deepened my relationship with sound which I am grateful for.
"I feel good about joining the Guildhall School."
Jack, 25, is in the first month of a Masters in Leadership programme and is studying alongside two percussionists, a classical flute player, a pianist, and a french horn player at what is one of the world's leading conservatoires and drama schools.
Jack, from Haringey, North London, said he felt daunted walking into the Guildhall and "ridiculous" sitting in a waiting room alongside opera singers and violinists before his audition.
He needn't have worried.
Sean Gregory, the Guildhall School's Director of Creative Learning, said: "In some instances, Jack showed more confidence with beats and rhythms than the instrumentalists."
Jack, one of three rappers who call themselves Strangelove, said the Guildhall programme will open new doors for him but he stressed he would not lose touch with his roots.