Heartfelt tributes have been paid to the young man who was the victim of a collision between two cars in Clontibret at approximately 11.30pm on Friday night.
It is understood he was travelling home after collecting his car following the match at Brewster Park when he was involved in a crash with another car near Tullybuck.
He was the driver of one of two cars involved in the collision and was pronounced dead at the scene.
The crash occurred hours after Brendan, starting at centre-back, played a key role as he captained Monaghan’s U20 side to victory in the Ulster championship semi-final against Donegal earlier that evening.
Monaghan recovered from a five-point half-time deficit to win 3-10 to 1-11.
He was a member of the Monaghan Harps GAA club, who announced that all activity at the club is postponed until further notice.
“Our club is devastated at the news of the untimely death of our senior player and county U-20 captain Brendan Óg Ó Dufaigh”, they posted on social media.
“Our thoughts are with his family and friends at this very sad time. All club activity has been postponed until further notice.”
The Monaghan County Board also extended their sympathies to the player’s family.
“Monaghan GAA are deeply saddened with the tragic passing of Brendan Óg Ó'Dufaigh, captain of the Monaghan U20 team, following a traffic accident last night,” they stated.
“We extend our heartfelt sympathy to Brendan Óg’s family, his father Brendan, his mother Esther and his sisters Claire and Áine and to his friends, his teammates and his club Monaghan Harps. Our thoughts and prayers are with his family at this very difficult time.”
Annagry Parish posted on Facebook: “Today we remember in our prayers Brendan Óg Duffy captain of the Monaghan U20 GAA team who sadly passed away last night.
Condolences to his father Brendan a teacher in Coláiste Bhríde, Rann na Feirste, his mum Esther & sisters Claire & Áine.”
His local club Monaghan Harps tweeted: "Our club is devastated at the news of the untimely death of our senior player and county U20 captain Brendan Óg Ó Dufaigh.
"Our thoughts are with his family and friends at this very sad time. All club activity has been postponed until further notice."
Gardaí are appealing for witnesses with any information related to the crash to come forward by contacting Monaghan Garda Station on 047 77200, the Garda Confidential Line on 1800 666 111 or any Garda station.