Robertson, 29, who left the Scottish side on Wednesday, is not eligible for the Dons' game against Chesterfield.
"I've had experience of League One before with Preston and Port Vale and I know what the league is about," Robertson told the club website.
"I know what we have to do and hopefully I can help get results for the team, the manager and the fans."
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AFC Wimbledon have signed former Ross County defender Chris Robertson subject to international clearance.