UFC officials announced the move on Monday.
Riddle was popped for marijuana usage following his last fight at UFC 149 in Calgary in July. His victory over Chris Clements was subsequently overturned and ruled a no-contest.
He was also handed a 90-day suspension, which is now expired, allowing Riddle to take a fight at UFC 154.
Riddle will face Besam Yousef on the Facebook preliminary fights for the upcoming card in Montreal.
UFC 154 takes place on Nov 17 from Montreal, headlined by UFC welterweight champion Georges St-Pierre in his return bout as he faces interim champion Carlos Condit.
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