The 20-year-old centre-back is available to make his Shots debut at home to Port Vale this weekend.
Hector was earlier on Thursday formally recalled by the Royals from from his loan stint at Shrewsbury.
Hector had been due to remain with Shrews until January but was sent back by Town boss Graham Turner two weeks ago in order to train and play reserve games to gain more experience.
Shots manager Dean Holdsworth said: "We have watched Michael a number of times since last season. He impressed last season when he played for Barnet.
"He can play in two or three positions as a defender or in midfield. He also has experience in a higher division and his adaptability is key for us too."
Meanwhile, Aldershot midfielder Scott Donnelly has left the club after the expiry of his short-term contract.
Holdsworth added: "It's key for Scott to get a run of games. I wish him well and thank him for what he has done for us."
Loanees Myles Anderson and Jack Munns have also returned to Blackburn and Tottenham respectively, while Doug Bergqvist and Jordan Roberts are back in Town's squad after returning from loan spells.