The move means that the Durham-born defender will return to Croft Park for the third time in as many years.
The central defender scored two goals in 17 appearances for Spartans during the first half of the 2018/19 National League North campaign and returned for a second loan spell earlier this year.
However, he was only able to make a further three appearances before the coronavirus epidemic brought a premature end to last season.
His latest temporary switch to Croft Park also means that Michael Nelson will become the third different permanent manager Cunningham has played under across his three loan spells at the club.
After completing the season-long switch, the defender revealed that that the Pools legend was a big draw in his decision to return to Northumberland.
He said: “He was a massive part in the move because he’s known as a Hartlepool United legend and I know he was really strong in the position that I play.
“That’s part of the reason why I wanted to go to Spartans.
“It will be good to go there and learn from him as a defender and learn from the experience that he had as a player.
“I just want to do my best for the club, I don’t look at the bigger picture or try to look at the long run.
“I just want to get games under my belt; I just want to help the club win games and take things game-by-game.
“We have to think positive and go into every game thinking that we can take points.”
Spartans boss Nelson revealed that he was made to wait to complete the deal as he fought off competition from two other clubs that had showed an interest in Cunningham.
He told the club website: “I’m really happy. It’s one we’ve been looking at for a while.
“I’ve been speaking to Hartlepool about him and we’ve had to wait for them to bring players in so Aaron could be loaned out.
“When we thought we did have it all agreed, there was a little bit of a stumbling block for one reason or another – a couple of other clubs came in and tried to sign him.
“To be fair to Hartlepool, we have to give them credit. They stuck to their word and we’ve managed to get it over the line today when it looked like it was going to be dead in the water.”
Spartans are awaiting confirmation over Cunningham’s availability for Tuesday night’s National League North season opener at Guiseley.