The musician, real name Mark Orabiyi, 35, was found with stab wounds by paramedics on the morning of June 5 and was pronounced dead at the scene.
Grammy winner Riley worked on tracks for artists including Dua Lipa, Zendaya, Khalid, Flo and Chipmunk.
His brother Michael Orabiyi, better known as record producer and songwriter Scribz Riley, wrote on Instagram: "My heart is shattered! This doesn't feel real. It feels like a bad dream.
"Just before he went to sleep we spoke about the future, staying positive and about everything we still had left to do. I never imagined that would be our last conversation."
He described his brother as "a friend to many, a mentor, an inspiration, and a light in so many people's lives".
"He loved deeply, gave freely, and touched countless people through his talent, kindness, and spirit.
"The outpouring of love already shows how many lives he impacted. You inspired so many people and your legacy will continue to live on through your music, your family, your friends, and everyone blessed enough to have known you."
Stormzy commented on the post, "I'm sorry bro", while JLS star Williams wrote: "Sending you and your family strength and prayers in Jesus name my brother."
British rapper Wretch 32 said: "Sending love to you & your family bro. Your brother was a gem & will be missed & never forgotten, Never! RIP."
Orayibi worked on hits including Khalid's Young Dumb & Broke, The Chainsmokers' Who Do You Love, HER's Lights On, Flo's Walk Like This, and Kehlani's Out The Window.
Police were called on Friday to reports that a man had been stabbed in the street of the London district of Silvertown.
Riley was found with stab wounds in the garden of a nearby property.
Three people were arrested later that day on suspicion of murder.
A 27-year-old man has been released on bail pending further enquiries.
After police questioning, a second man, aged 24, and a 25-year-old woman have been released with no further action.
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