The 40-year-old - known fondly as Grezza to his teammates - came off the bench to sensationally score an injury-time free-kick and secure a 2-2 draw against League One champions Charlton on Saturday.
The trademark strike brought down the curtain on a professional career spanning 1,023 appearances that saw the former Scotland international honoured with a PFA Merit award at the players' union's end-of-season awards gala last weekend.
"It was a tough decision to retire but it's the right one," he told the Lancashire Evening Post. "The occasion was very emotional, there were a couple of times when I had to keep myself in check.
"I felt emotional driving to the ground on Saturday morning because it was my last day as a player. Then I got quite nervous about actually going out there and doing a job - things just took over me when I scored.
"My wife, kids and dad were in tears, I know that because my kids told me when they came on the pitch at the end."