Gqozo told Sapa in an exclusive interview that he had written to the commission on Monday, informing it of his intention to testify.
"Many things have been misrepresented on this and other issues. It is good to be given the chance to tell the public of South Africa exactly what happened."
Referring to the day of the massacre, he said: "I never wished anybody any harm. I was doing a job under very difficult circumstances. My only concern at the time was that nobody should come to any harm.
"It happened but I could not control it."
Speaking from an undisclosed venue, Gqozo said he supported the work of the Truth Commission and viewed its chairman Archbishop Desmond Tutu as an honourable man whom he respected and trusted.
"South Africa needs to be healed," he said.
Gqozo said he was prepared to co-operate fully with the commission's investigations into human rights abuses in the former Ciskei.
He will be joined at the hearing on Tuesday by his legal counsel, Bisho-based advocate Sally Collett.
"I am trying to make a break with the past. The main thing now is that I am not in hiding. I am not afraid. I support the efforts of the government to bury the hatchet," he said.
Gqozo was sentenced to a R10,000 fine or two years' imprisonment by a North-West magistrate last week after being convicted of illicit diamond dealing.
There have been weeks of speculation about whether or not he would accept the commission's invitation to testify at the three-day hearings on the massacre at the Bisho campus of Fort Hare University.
Eastern Cape commission head Bongani Finca received Gqozo's letter on Monday while the commission was listening to testimony from Ramaphosa, who was making a submission on behalf of the ANC.
Ramaphosa told the commission that the massacre had been a well-planned trap in which scores of ANC marchers were killed and injured by Ciskei Defence Force troops who opened fire on them near Bisho stadium.