But despite her pleas to end gun violence, the eight-time Grammy Award victor has previously been accused of glamorising the use of firearms.
He is said to have been walking near his home in Lakes Close, Eden Lodge, St Michael at around 7pm when he was approached by a man who shot him multiple times and fled the scene. Alleyne died at hospital.
Rihanna shared her deep sorrow for the loss of Tavon on her official Instagram account.
Rihanna's touching post included a gallery of four photographs, showing the two of them together.
"Never thought that would be the last time I felt the warmth in your body!" Back on February 20, Alleyne celebrated his cousin's birthday with her, affectionally saying how her presence is "a source of joy and happiness" to him.More news: Cold continues... Snow showers late today
The 29-year-old ended her post by hashtagging "end gun violence".
Rihanna pointed out how frail life can be and no one ever knows the day or hour when those we love will be gone forever.
Gun crime has been rife on the Caribbean island recently with police confirming a significant increase, with 22 out of 28 murders committed there being gun-related. "❤ #endgunviolence", she wrote alongside the snap that she has uploaded to the photo-and-video-sharing application.