Alexander made his debut for the Iron in 1991, famously missing a penalty in the 1992 Division Four play-off final loss to Blackpool, before going on to play for Luton, Preston and Burnley.
He is currently in his second spell at Deepdale, and acted as joint caretaker manager alongside David Unsworth when former boss Phil Brown was sacked earlier this season.
He was given the PFA Merit award to recognise his 20 years in the professional game.
"To get recognition for what you have done in your career at any stage is great," he said.
"I'm coming towards the end of my playing career and I'm privileged to be recognised by the people who I have played against for the last 20-odd years."
The PFA League One team of the year, voted for by players including the Iron's, was dominated by champions Charlton who provided four names.
Sheffield United striker Ched Evans' inclusion was unsurprising - he has netted 35 goals for the Blades this season - but raised eyebrows considering his conviction for rape on Friday.
League One team: Ben Hamer (Charlton), Jack Hunt (Huddersfield), Michael Morrison (Charlton), Harry Maguire (Sheff Utd), Rhoys Wiggins (Charlton), Johnnie Jackson (Charlton), Stephen Quinn (Sheff Utd), Stephen Gleeson (MK Dons), Darren Potter (MK Dons), Jordan Rhodes (Huddersfield), Ched Evans (Sheff Utd).