The Danish international, who was born in London, agreed to a five-year deal that would expire in June 2029.
O'Riley, 23, won six medals, including three Scottish Premiership titles, and scored 27 goals in 124 games for Celtic.
#brighton
The Danish international, who was born in London, agreed to a five-year deal that would expire in June 2029.
O'Riley, 23, won six medals, including three Scottish Premiership titles, and scored 27 goals in 124 games for Celtic.
#brighton