Alexander returns to the club with the Lilywhites second bottom of the Championship with four points from eight matches.
He departed Bradford to return to Deepdale, having led the Bantams to the top of League One after seven games this season as well as promotion from League Two after initially taking charge in November 2023.
Prior to his time with Bradford, Alexander had a brief caretaker spell in charge at Preston in 2011-12 and also spent time as boss at Fleetwood, Scunthorpe, Salford, Motherwell and MK Dons.
He said that on arrival at Preston, he wants his players to turn out for each other and their long-term prospects, rather than just to impress him personally.
“It’s not about wanting to play for me, it’s about playing for each other, it’s about playing for the club,” he added.
“I’m not into it where you’re running for your manager. You’re running for your team-mates, you’re running for your career, you’re running for your family, that’s where it is.
“I’m just here to guide them and to bring them all together.”