The 28-year-old midfielder took the decision to leave Oldham Athletic at the end of last season when his contract expired.
He had an offer from Doncaster Rovers on the table, but turned that down in the belief that Millwall would put terms to him after a trial spell.
No contract arrived, though, and Croft was left on the shelf.
He has now landed himself a short-term deal at former loan employers St Johnstone - through to the end of the current campaign - and is delighted to be back in familiar surroundings.
Croft said in the Daily Record: "I enjoyed my time here on loan from Derby and it is good to come back. I know what the club is all about, many of the same players are still here and manager Tommy Wright has been keen to bring me back.
"The initial contract is through to the end of the season but there is an option to extend it.
"It's great to finally get myself settled. I've had a frustrating time of it since the summer.
"I had a great season last year with Oldham, one of the best years of my career, but got messed around after turning down an offer tabled by Oldham.
"I was led to believe there would be a deal for me elsewhere and turned down interest from Doncaster because Millwall wanted me.
"But the weeks went by and eventually (Steve) Lomas had brought in other players and said his budget was spent. He had brought me to Perth on loan so it left a sour taste in the mouth.
"It led to a frustrating period but now it's behind me and I can focus on my football again. If anything, it's made me even more determined to enjoy the rest of the season here."