Williams made 125 league and cup appearances for Manchester City between 1980 and 1986 and also had brief spells with Queen of the South and Port Vale.
[7] He was scouted by Manchester City coach Steve Fleet at the age of 14 and signed a two-year apprenticeship with the club upon leaving school in May 1978.
[16] The Manchester Evening News' Football Pink wrote that "Alex Williams today set a record by becoming the first coloured goalkeeper to make the breakthrough at First Division level".
[18] However, he was not selected for City's 1981 FA Cup final appearance at Wembley Stadium, as manager John Bond opted to fill the substitutes bench with outfield players.
[20] He experienced racist abuse due to the colour of his skin, but stated that "I was immune to the insults and we refused to bow to the bigots, determined that prejudice would not prevail".
[20][24] City won just three of their last 18 league matches and were relegated out of the First Division with defeat at home to Luton Town on the last day of the season.
Despite this, Williams – who had played all of City's 46 games, picking up six man-of-the-match awards – was voted onto the PFA Team of the Year, along with teammate Mick McCarthy.
However, he lost his first-team place to Eric Nixon due to injury eight games into the season and fell further down the pecking order with the arrival of Perry Suckling.
[11] His last game for the club was a 3–0 home defeat to rivals Manchester United on 14 September 1985, when he gave away a penalty after fouling Mark Hughes.
[29] He made the club aware of severe back pain he was suffering after the match and was diagnosed with a slipped disc by a specialist, who recommended six weeks of total rest.
[32] Williams was deemed fit enough to play, though not to top-flight standard, so went on loan at Scottish First Division club Queen of the South in September 1986.
[34] Williams recalled receiving a different kind of abuse in Scotland, remarking that he was "referred to as an English bastard, rather than for the colour of my skin".
[35] He played five games for Queen of the South, though found himself unable to perform to the same standard as before his injury, which convinced City chairman Peter Swales to let him leave the club.
[44] He returned to Port Vale in July 1988 as the club's first community programme officer, but departed in January 1990 to take up a similar role at Manchester City.