Alexander, 40, came off the bench for the final minutes of Preston's League One game against Charlton at Deepdale.
Lilywhite boss Graham Westley sent him on to give fans the opportunity to show their respects, and he curled home a stoppage-time free-kick to earn his side a 2-2 draw.
"You simply couldn’t make that up, could you? That was sensational. I am so, so pleased for Graham,” said Westley.
“If ever there was a man that deserved a moment like that it’s him, isn’t it? It was the most incredible moment and everyone in the whole ground was just so pleased for the man.
“He thought he had about two-and-a-half minutes in his legs, so when I put him on for six it was a bit of a shock to him."
Alexander began his career at Scunthorpe, making his derby in April 1991. He made more than 200 senior appearances for the Iron before joining Luton Town in 1995 for a fee of £100,000.
He has had two spells at Preston, sandwiched between a memorable period at their Lancashire rivals Burnley as he helped them win promotion to the Premier League. He became, at 39, the oldest player to make a debut in the Premier League.
Although born in Coventry he made 40 appearances for Scotland, and became the second outfield player in English football to make 1,000 professional appearances (Tony Ford, another former Iron, was the first).