He also played as a professional for Halifax Town, Everton, Rotherham United, N ottinghamshire County, Sunderland, Manchester City, Aberdeen, Tottenham Hotspur, Crystal Palace, Preston North End, York City and Mansfield Town. He is the current goalkeeping coach at Bolton Wanderers. Born in York, Mimms began his football career as an apprentice at Halifax Town.
However, he failed to break into the first team and joined Rotherham United in November 1981 for a fee of £15,000.
During the 1980s, Mimms played for no less than eight different clubs, as he went out on loan from Everton more than once. However, due to an injury to Neville Southall, Mimms played in goal for Everton in the final weeks of the 1985-1986 season.
Everton were top of the league for most of the last three months of the season, but were pipped to the title on the last day by local rivals Liverpool. He was later sold to Tottenham Hotspur in 1988 following the retirement of Ray Clemence, and had more first team chances at White Hart Lane than he had been given at Goodison Park.
In December 1990, Blackburn Rovers manager Don Mackay signed him for a fee of £250,000 from Tottenham Hotspur making him Blackburn"s most expensive transfer at the time.
He was signed in the early stages of Jack Walker"s backing of Blackburn, and just weeks before Walker took full control of the Second Division club Blackburn had a slow start to the 1991-1992 season, and Mackay was sacked in early September, being replaced the following month by Kenny Dalglish. Dalglish made several substantial signings during the season and Blackburn reached the playoff final where they beat Leicester City 1–0, ending 26 years outside the top flight.
Mimms was one of the players who kept his place in the team throughout the season.
Mimms was an integral part of this team However, Jack Walker was not one to rest on his laurels and after the club"s promotion vast amounts of money were spent to recruit the finest talents in the country to Ewood Park.
In November 1993, Southampton goalkeeper Tim Flowers was brought in as the new number one. From then on, Mimms was rarely selected in the starting line-up, his four appearances in the 1994-1995 season not being enough for a title medal, and in early 1996 joined Crystal Palace, where he played just once.
He then dropped into the lower divisions, playing for Preston North End, Rotherham United, hometown club York City and finished off his playing career at Mansfield Town in 2001.
Between 2001 and 2008 Mimms worked as goalkeeping coach at Wolverhampton Wanderers, before returning to Blackburn to fulfil the same role in August 2008. until he was sacked on 27 December 2012. During the pre-season preceding the 2013/14 season Mimms was appointed goalkeeping coach at Oldham Athletic. In February 2014, he left his role at Oldham to join the Bahrain national football team as their new national team goalkeeping coach.
In October 2014 Mimms was appointed as goalkeeping coach at Premier League side West Ham United.