After 12 years of hearings and an estimated cost of 191 million pounds (230 million euros), the 5,000-page report will be released at 3:30 GMT. That makes it the longest and most expensive inquiry in British history.
The new report concludes that several of the fatal shootings were unlawful, according to an article in British newspaper The Guardian, which suggested that the report would put "severe pressure" on Northern Ireland to prosecute soldiers for the killings.
Victims' families conducted a silent march this morning to the Guildhall in the city of Derry - the same route that was cut short by the shootings 38 years ago.
Bloody Sunday was a benchmark incident in the Troubles, three decades of sectarian violence in which more than 3,500 people died. The Troubles largely came to an end with the 1998 Good Friday Agreement.
An initial inquiry into Bloody Sunday largely let British soldiers off the hook, saying simply that their acts "bordered on the reckless." Many insiders say this ruling boosted the Provisional Irish Republican Army's popularity in the province and incited further violence.