Work by the Police Ombudsman was suspended following a Criminal Justice Inspectorate (CJI) probe in 2011 that found the way in which the Ombudsman's office conducted its investigations compromised its independence.
But on Wednesday, the CJI Chief Inspector said "substantial progress" had been made by the Police Ombudsman Northern Ireland (OPONI) and recommended the Ombudsman's office should recommence their work on the cases.
"New structures and processes had been put in place within the OPONI which focused on providing comprehensive and robust quality assurance of investigations into historical cases and the subsequent production of public reports," said Brendan McGuigan.
The CJI found reports by the Ombudsman's office had been influenced and buffeted by feedback from families, their legal representatives and the PSNI.
It led to the resignation of Chief Executive Sam Pollock, who claimed the Ombudsman's office lacked independence.
NI Police Ombudsman Dr Michael Maguire said he believed his office could now investigate the matters in an independent manner.
"Under the law, the PSNI's Historical Enquiries Team has had to refer certain incidents during 'The Troubles' to my Office for independent investigation," he explained.
"Members of the public across the community have also made complaints about serious matters, including deaths, during this period."
"We have more than 150 such cases which we must now consider. It is important that these matters are dealt with," added Dr Maguire.
Justice Minister David Ford said the announcement was a positive development.
I am conscious of the distress the decision to suspend the investigations caused the families, police and the wider public.
Justice Minister David Ford
He added: "It is however vitally important that there is public confidence in the way in which investigations are carried out and reported."
Mr Ford said his department is continuing to work on proposed changes to the structure, role and powers of the Police Ombudsman's Office.
Mr McGuigan said the CJI will revisit the issue once further historic reports have been published.
The Ombudsman's historic investigations unit, which has a staff of 40 and an annual budget of £2m, will to look into allegations of RUC involvement in criminality between 1968 and 1998.
It is expected to complete two complex investigations - some of which may be linked to 20 others - and six stand-alone cases each year.
The director of the Committee on the Administration of Justice (CAJ), Brian Gormally welcomed the announcement.
"CAJ welcomes the positive report by Criminal Justice Inspection into the Office of the Police Ombudsman and the recommendation that investigations into historic cases be re-started," he said.
"CAJ brought to light the undermining of the independence of the Office under the previous Ombudsman and is pleased to see that many of the issues have now been addressed.
"However, the Chief Inspector has correctly stated that the Inspectorate could only truly assess whether or not the full independence of the Office had been restored after public reports on historical cases had been published and that he will return to the issue once this has happened."
Mr Gormally said the committee would monitor the Ombudsman's process of reform.
Sinn Féin MLA Gerry Kelly said he hoped the Ombudsman's office can carry out the investigations "efficiently and speedily".
"This is welcome news for the families of the victims and it is crucial that they have confidence in the office to carry out these investigations.
"Under these processes installed by the new Ombudsman Michael Maguire, which have been approved by the Criminal Justice Inspectorate, the investigations should proceed free from interference," he said.
But DUP MLA Paul Givan said the office should focus on current issues within the PSNI and his party are opposed to the historical investigations.
"It has been used by republicans and nationalists as a means to further their efforts at re-writing history by creating a narrative that only deals with deaths were the security forces was involved whilst the main terrorist organisation namely the IRA is not subjected to the same scrutiny."