Kevan linked up with the Robins in September in a part-time coaching capacity, with the 45-year-old counting Burnley, Notts County and Stoke among his former clubs.
And following Pennock's appointment on Tuesday as the new manager of Forest Green, replacing Dave Hockaday, Kevan has opted to link up with him at the Skrill Premier outfit.
"Dave has been great around the place since being here," Cheltenham manager Mark Yates told the club's official website.
"He came here on a part-time basis but he now has the opportunity of a full-time position with Forest Green. I'd like to thank Dave for his efforts and we all wish him the very best."
- Sports & Recreation
- Dave Hockaday
- Notts County