Commons was a controversial exclusion for the World Cup double header after arguably being Celtic's best player this season.
But the 29-year-old, who last played for Scotland in a friendly defeat by Brazil in March 2011, has been drafted in after Norwich winger Snodgrass failed to overcome the ankle problem which kept him out of action at the weekend.
Blackburn striker Rhodes has also withdrawn with an ankle injury.
Snodgrass started the goalless draw with Serbia last month and Rhodes came off the bench against both Serbia and Macedonia.
Commons was last named in a squad for the friendly against Denmark at Hampden on August 10. But the former Nottingham Forest and Derby player turned up at the team hotel with a protective boot on after suffering a foot injury for Celtic and was eventually ruled out.
He was also forced to withdraw from the previous squad, for the Carling Nations Cup games against Wales and the Republic of Ireland in May 2011. He was sent home by the Scotland medical team with tight hamstrings after reporting to the team hotel.
The decision by Craig Levein was his second apparent u-turn in a week: striker Steven Fletcher was named in the original squad last week after making peace with the manager.
Commons, who has scored two goals in nine international appearances, struggled with form and fitness for much of last season but has re-established himself as a key player for Celtic in an advanced midfield role this term.
Scotland manager Craig Levein previously said there were more than half a dozen players ahead of Commons in his position and that he was "really unlucky" to be left out of his initial squad.
Commons last week admitted his exclusion had left him "baffled" and later told Celtic's matchday programme that his international career was the last thing on his mind.
Today's developments mean Levein has 22 players available for the Cardiff City Stadium clash on Friday night and the game in Brussels four days later.
Steven Naismith had previously dropped out of the squad after being handed a two-match FIFA ban for elbowing Serbia's Srdjan Mijailovic while Blackburn defender Grant Hanley pulled out on Monday with a groin strain.