South Africa youth international Radebe died in a car crash in his hometown of Newcastle on Tuesday.
The Aspire Academy product helped KA Eupen gain promotion to the Belgian topflight this past season, having joined the club in 2012.
Radebe grew up with Hlanti and they would often catch up in Johannesburg during the off-season.
"He was a very close friend of mine and, as much I was a little older than him, he grew up with me. At all the times when he's back in the country, he didn't hesitate to see me. So it hurts so much, especially for his family," a shattered-sounding Hlanti tells KickOff.com.
"Even us in South Africa, we lost a good player. His father and his mother... this is so sad. I was always in contact with him, even when he was in Belgium. So to me he was like my brother because he was always willing to learn, and we used to speak on several things of life. Ntuthuko didn't have that 'I'm old to him' and it was always like brothers as I've said, but life goes on. I'll bear the pain of his death."
Radebe's representative Sizwe Ntshangase, who spoke to the fullback on Monday, also offered his heartfelt condolences to his family while revealing the player was in demand both locally and abroad.
"I last spoke to him yesterday [Monday] at 17h30 when he phoned me because there were interested clubs in the PSL. But he was supposed to return abroad next week because Eupen were offering him another two years," Ntshangase says.
"But there was also another offer in France through my colleague who represented him in Belgium.
"His death is a sad loss. Here, we are talking about a player who was playing similar to Tsepo Masilela. He still had years ahead of him and he was still going to bomb [explode] in South Africa even though he never played for any local club.
"The day he landed in South Africa, he phoned me and then we spoke at length about his wish to come back and play in the PSL for at least one season.
"He had qualified to play to any league in Europe because he had obtained the European passport.
"As a South African, we lost a good player and our condolences goes to his family."