The residents, many of whom are now elderly, alleged they were abused and neglected while living at the Huronia Regional Centre in Orillia, the Rideau Regional Centre in Smiths Falls and the Southwestern Regional Centre near Chatham.
All three institutions shut down between 2008 and 2009.
A $35-million settlement in the Huronia case was reached in September 2013 and approved by the court in December of that year; a $32.7-million settlement in the Rideau and Southwestern suit was reached that same month and approved in February.
The Huronia settlement led Premier Kathleen Wynne to apologize in the Ontario legislature for the suffering residents experienced there.
The agreements have also forced the province to release more than 65,000 documents about operations at all three institutions.
"These cases concern abuse that happened decades ago when many of the former residents were children and young adults," said Kirk Baert, who represents the plaintiffs.
"I am happy that we are approaching a final resolution of these cases and that the former residents will be able to receive what is long overdue compensation."
Former residents have been able to request records of their stay as they prepared to apply for compensation. While the records aren't required to file a claim, the agreement said more money would be awarded to those who provided more detailed accounts of what they endured.
So far, more than one million pages of resident records have been released, lawyers said.
The claim deadline for Huronia was initially set for August, but was pushed back after some residents said they were facing delays in obtaining their files.
A spokeswoman for the Ministry of Community and Social Services said 2,644 requests were received before the initial August deadline. Of those, 40 files could not be located, Kristen Tedesco said in an email.
As of Wednesday, another 358 requested had been received, and 307 of them completed, she said. Those whose files couldn't be delivered by the deadline were given a letter confirming that they had lived in one or several of the facilities, she said.
"It’s important to note that many of the files are several decades old and they are all paper-based," Tedesco said.
"The files may also relate to individuals who moved several times within the facility system, and their files may have moved with them."
The lawsuits alleged many suffered physical and sexual abuse at the overcrowded and understaffed prison-like institutions.