Philomena Lee was forced to give her three-year-old son up for adoption in rural Ireland in 1952.
Her story has been made into a film - Philomena - starring Dame Judi Dench.
Mrs Lee has now launched a campaign calling for the release of more than 60,000 adoption files held by the Irish state, churches and private agencies.
The files contain information on the identities of parents and children affected by adoption, which was sometimes forced upon
The Philomena Project was launched in Dublin on Friday, in collaboration with the Adoption Rights Alliance.
Speaking about the event, Mrs Lee said: "I've been so moved by the support we've received, both for telling our story and for bringing attention to this experience that so many of us had.
"My daughter Jane and I established The Philomena Project because we've heard from so many people who saw my story and want to help.
"It is my hope that this effort will help us find solutions that ensure every mother and child who wants to be reunited are able to come together once again."
Mrs Lee, who was single when she became pregnant at the age of 18, was sent to a residential home for unmarried mothers in Roscrea, County Tipperary.
The home was run by the Catholic Church, and when her son was three years old, Mrs Lee was forced to agree to his adoption.
The boy was sent to a family in the United States, and despite both embarking on long searches in a bid to find each other, her son died without seeing her again.
During their search, Mrs Lee's adult daughter approached the journalist Martin Sixsmith, to enlist his help. He turned their story into a book - The Lost Child of Philomena Lee.
The film version of his book, which was partly shot in Northern Ireland, has just been nominated for four Oscars, including best picture and best actress.
The Philomena Project is supported by the Adoption Rights Alliance, founded in 2009 "to campaign for equal human and civil rights for those affected by Ireland's closed, secret adoption system".
Its co-founder, Susan Lohan, said: "The strength, courage and dignity of Philomena Lee has acted as a touchstone for all of those affected by forced and illegal adoptions.
"Her story and that of her son recounted so eloquently in both in the Lost Child of Philomena Lee and in the film adaptation Philomena have woken up many people to the crimes committed against thousands of unmarried mothers and their children under the guise of so-called legal adoption."