Eskom's acting chief executive officer Willem Kok made the apology at the Truth and Reconciliation Commission's special hearing in Johannesburg on the role of business in apartheid.
The electricity supply commission acknowledged that it did not always behave like a model corporate citizen, and that the industry had reflected the peculiarities of apartheid.
The Electricity Act, which granted local authorities sole control over electricity supplied within their areas of jurisdiction, often caused the separation of naturally integrated networks, Kok said.
"Separating the administration of black urban areas from white cities often meant that the black areas were left without electricity services."
Eskom initially took no positive action to broaden access to electricity and it did not challenge racial policies that prevented investment in and development of townships.
However, since 1987 Eskom had become involved in the supply of electricity to black local authorities.
Kok said Eskom was severely affected by international sanctions and the policy of disinvestment during the apartheid years.
Referring to trade union activities, he said Eskom's status as a so-called parastatal organisation did not prevent its employees from joining unions. The company's relationship with unions dated as far back as 1919.
Unions now had a say in corporate governance and were playing an important role in Eskom's future through representation on the Electricity Council, its medical aid and pension scheme.
Kok said Eskom's affirmative action target was to ensure that 50 percent of all professional, senior supervisory and management staff would be black by the year 2000.
Apologising for mistakes of the past, Eskom said until the late 1980s, as a public utility, its actions and policies did little to improve the plight of blacks in South Africa.
As an employer, its employment practices were largely discriminatory.
"Eskom wishes apologise to all black South Africans in general and black Eskom employees in particular for the fact that it entertained apartheid policies and, through its actions, perpetuated it.
"In addition, Eskom wishes to apologise to all South Africans, regardless of race or colour, for the fact that, as a major player in the South African industry and the economy as a whole, it did not take active steps to facilitate the demise of apartheid and racial discrimination.
"Also, for not using its link with the government to influence its thinking and apartheid-based policies," Kok said.
Eskom believed that it could in future play a major role in reshaping the country and pledged its commitment to righting the wrongs of the past.