The Austrian, who was rumoured to be heading to Sunderland earlier in the week, has chosen to make a popular return to the DW Stadium on loan from German club Hamburg SV.
Scharner became a cult hero for Wigan when he was signed by Paul Jewell in January 2006 from SK Brann.
He went on to play 145 times for the Latics over four seasons, including representing them at the 2006 League Cup final, and he scored the first goal in the final day escape from relegation at Sheffield United in May 2007.
Scharner moved to West Brom in 2010, before quitting the Premier League for Hamburg last summer. He has struggled to make an impact at the Imtech Arena thanks to injuries.
Scharner said: “It really is fantastic to be back.
“Wigan will always have a big place in my heart, so to be asked to come back and help the team now is something really special for me.”
Scharner will wear the no.33 shirt and will provide short-term cover for Ivan Ramis, who is ruled out for the rest of the season after damaging ligaments in a draw at Fulham earlier in the month.
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