Irwin began his playing career at Leeds United as a sixteen-year-old, where he made a total of 72 appearances before being released as a 20-year-old to Oldham Athletic. He then moved to Oldham Athletic He played in the 1990 League Cup final and the FA Cup semi-final against United, in which his performance won him a move to Old Trafford in a £650,000 deal and he celebrated 10 years at Old Trafford with a record-breaking testimonial against neighbours City in August 2000.

More success followed with a European Cup Winners' Cup medal in 1991 before winning the Premiership in 1993, as an ever-present member of the team, playing in 40 League games, scoring five goals

He is now United's most decorated player having won six Premiership titles, two FA Cup winners' medals and a Champions League medal. He also holds the club record for appearances in the European Cup.

During the historic 1998-9 season, he was harshly sent off against Liverpool for kicking the ball away and was forced to miss the FA Cup final through suspension.

He has played in total of 505 games for Manchester United and has scored 33 goals between 1990 and 2001. He has also won many medals with Manchester United including; the European Cup Winners Cup, the European Super Cup, Premier League 6 times, FA Cup 3 times, League Cup and the European Champions League.

Irwin first played for Manchester United at right back, but was switched to left back in the 1991/1992 season, and was virtually the first name on the team sheet, until Phillip Neville came along. Irwin has also played international football for the Republic of Ireland, having played in 56 games and scoring 4 goals.

At the age of 36 and with younger and new stars at the club, the opportunities for playing on the hallowed turf of Manchester United became less frequent, so Wolves snapped him up for a final season or two to see if his experience at the back will be enough to finally take the Molineux side back into the top flight.