Sean was due to get married this August to his fiancee Holly McConnellogue who he met in Derry three years ago.
At a ceremony in the UN General Assembly Hall, Irish Ambassador to the United Nations Fergal Mythen will receive the Dag Hammarskjöld medal on behalf of the family of Private Rooney.
The medal ceremony forms part of a series of events planned to mark the 75th anniversary of United Nations peacekeeping.
Secretary General of the United Nations António Guterres will lay a wreath at the Peacekeepers Memorial in the grounds of the UN compound to commemorate the 4,200 peacekeepers, including 91 Irish personnel, who have died.
Speaking ahead of the anniversary, Mr Guterres said UN peacekeepers were “the beating heart of our commitment to a more peaceful world”.
“For 75 years, they have supported people and communities rocked by conflict and upheaval across the globe. Today, on the International Day of United Nations Peacekeepers, we honour their extraordinary contributions to international peace and security,” he said.
Ireland has contributed peacekeepers to UN missions on a continuous basis since 1958.
Today, there are nearly 500 Irish police and military personnel serving under the UN flag.“We remember the peacekeepers themselves but at this time we remember the families who deal with their tragic loss on a daily basis,” said Major General Maureen O’Brien, who is seconded from the Irish Defence Forces to the United Nations, as Deputy Military Adviser to the UN Secretary General on peacekeeping.
“We use their work and their loss tragic loss as an inspiration for us going forward and to remember the work that we’re doing although it can sometimes be dangerous it is worthwhile,” she told RTÉ News.
The first official UN peacekeeping mission was the deployment of military observers to the Middle East in 1948 to supervise the implementation of Israel-Arab Armistice Agreements, in what became known as the United Nations Truce Supervision Organization.
According to the UN, two million peacekeepers from 125 countries have since served in 71 operations around the world.
Currently, 87,000 women and men are serving in 12 conflict zones across Africa, Asia, Europe, and the Middle East.