Newcastle is searching for a new manager after Benitez left for China following the expiry of his contract at the end of June.
Steve Bruce has reportedly emerged as the favourite, but another former Sunderland boss in Allardyce claims to have been contacted about the role, much to his own surprise.
The former Bolton Wanderers, West Ham and England manager spent eight unhappy months in charge of Newcastle before a parting of ways in January 2008.
"I was certainly extremely surprised," Allardyce said.
"It never really got to the sort of talks people are suggesting. I had to chat to my agent and, as much as I respect Newcastle, Newcastle fans and Mike [Ashley, Newcastle owner], it wasn't for me. I politely said no and moved on.
"It's that thing [in your mind]... don't go back.
"Maybe if it was the first time around I'd have jumped at it, but not now. I appreciate the offer. I was very flattered that I was being considered.
"I had a think about it, but it wasn't something I thought about too long. It was better that I made a quick decision for everybody because they're in pre-season now.
"I never got to talk to Mike, it was just my agent contacted me and I had a quick think about it and a look at the situation. [It was] not for me."
Allardyce, 64, has not held a full-time coaching role since leaving Everton in May 2018.