Randall, who agreed the deal last week after leaving Italian club Ascoli, is eligible to feature in Saturday’s clash with Peterborough United at stadiummk.
The move sees the Milton-Keynes based playmaker return to the club where spent time on loan from Arsenal during the 2009/10 season.
“It’s taken longer to get over the line than we would have liked.” Karl Robinson told mkdons.com. “I’m now looking forward to having Mark available to select. He’s from MK, he’s a talented footballer and he suits our style.
“The first two weeks he trained with the youth team and I’d like to thank Mike (Dove) for his help with that. He then stepped up a grade into the first team and he’s done well. We’re low on numbers and it’s a chance for him to rekindle his career, just the same as Ryan Hall.”
The 24-year-old started his senior career with the Gunners, making his debut in the 2-0 Carling Cup win at West Bromwich Albion in October 2006. He went on to appear a further 12 times for Arsenal, including twice in the Premier League and twice in the Champions League.
Loan spells at Championship side Burnley, the Dons and Rotherham United followed before he moved permanently in the summer of 2011 to Chesterfield, where he won the Football League Trophy.
Mark will wear the number 15 shirt.