Dean Smith was confirmed as the new Villa manager on Wednesday night following Steve Bruce's sacking, with Terry joining as his assistant retiring from his playing duties last Sunday.
Terry was Villa's marque signing last season and helped guide the club to the play-off finals in June, where the club lost out to Slaviša Jokanović's Fulham side.
Terry has revealed he can't wait to get started on his social media platforms.
The former England and Chelsea captain wrote on Instagram on Thursday: "Delighted to be assisting Dean Smith at Aston Villa.
"Looking forward to my 1st steps into coaching and returning to a club where I have great memories."
Aston Villa are currently 15th in the Championship.