The black Mercedes-Benz hearse carrying the body stopped at a side entrance to the chapel and the coffin, which was draped in a white cloth with an arrangement of white flowers on it, was carried in by hand.
A large media contingent had assembled outside the crematorium, which is in the Eastern Cape, from early on Tuesday morning.
The family of Steenkamp, who was shot dead on Thursday at her paralympian boyfriend Oscar Pistorius' home, has asked the media to respect its privacy.
There was an air of restrained suspense at the tranquil, weather-beaten building, which is surrounded by large trees and terraced lawns.
The police warned local and international news teams to leave the premises and they retreated to outside the boundary wall.
Part of the crematorium, a memorial wall and several gravestones were visible from the entrance, where police had erected a cordon.
Some journalists said they had arrived at 6am to ensure they missed nothing ahead of the model's memorial service, but by 9.30am only police and Doves Funeral Service had arrived.
Soon after, the first mourners began to trickle in. Those who arrived on foot were swamped by reporters asking them for comment.
The weather was cool and slightly cloudy with a light wind blowing through the trees.
The Herald newspaper reported on Tuesday that Steenkamp's family had been besieged by the media.
Unlike murder-accused Pistorius' family, it is unaccustomed to being in the media spotlight.
Steenkamp's cousin, Sharon Steenkamp, said there would be a "media blackout" at the memorial service.
However, a press conference would be held afterwards, she said.