The 21-year old only joined the Cottagers from Manchester United on deadline but has now been sent to the DW Stadium for the remainder of the Championship season.
Tunnicliffe played twice for Fulham in the Premier League under former United assistant Rene Meulensteen but is not required by new manager Felix Magath and will now replace injured Latics midfielder Ben Watson for Uwe Rosler.
"Ryan is a very promising prospect player who has experience in the Championship, and after we lost Ben (Watson to broken leg), I am delighted we have got someone who is so football-educated, having come through the ranks at Manchester United under Sir Alex Ferguson," said the Wigan manager.
"He is a different type of player from Ben but will definitely add a new dimension to us."
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