Djilali spent last season at Kingsmeadow but the winger only six starts during an injury-ravaged spell.
He signed for Portsmouth over the summer only to be released due to doubts over his fitness.
"Kieran has been training with us for a month now," said Dons boss Neal Ardley after confirming the player had agreed a short-term deal.
"He has trained well and showed a very good attitude. He has the potential to play at a higher level but first he need to prove himself with us."
The 21 year old follows the signing of goalkeeper Neil Sullivan, who represented Wimbledon during their Premier League days and has similarly penned a short-term contract after leaving Doncaster.
The veteran 42-year-old stopper has not featured at the Keepmoat Stadium this term due to a hand injury.